End of an international armed conflict

Evaluating whether an armed conflict has come to an end may be a difficult undertaking. This is mainly due to the lack of detailed guidance in the 1949 Geneva Conventions on the subject but also to the fact that peace treaties are a less and less common State practice.

In the view of the ICRC, the starting point – based on the wording of the 1949 Geneva Conventions and Additional Protocol I, as well as international jurisprudence – is that, in international armed conflict, IHL ceases to apply on the general close of military operations, except for persons whose final release, repatriation or re-establishment takes place thereafter.Footnote ⁴ The general close of military operations, however, is not always easily determined, especially in the absence of ongoing hostilities.

International armed conflicts hardly ever give rise to the conclusion of peace treaties nowadays. Their waning days are more often characterized by unstable ceasefires, a slow but progressive decrease in the intensity of confrontations, or the involvement of peacekeepers. In a number of cases, there is also a significant risk that hostilities may resume. In addition to these and other features, it may be observed that the distinction between agreements aimed at suspending the hostilities and peace treaties is also becoming blurred. Ceasefire agreements may in fact have the effect of permanently terminating hostilities. Where this is the case, the precise labelling of a particular agreement may be of limited relevance for the purposes of IHL applicability. It is rather the resulting de facto situation that will define the real import of the agreement and its ability to objectively put an end to the armed conflict.

International case law has so far not proven to be sufficiently helpful on the issue of how to determine whether an IAC has ended. By way of example, in the Tadić case, the ICTY opined that in situations of international armed conflict IHL continues to apply “until a general conclusion of peace [has been] reached.” This, it may be pointed out, is a rather vague and impractical criterion.

As regards academic writing, the general view revolves around the following basic proposition: IHL applicability ceases once the conditions that initially triggered its application no longer exist. This means that an IAC ends when the belligerent States are no longer involved in an armed confrontation. The application of this proposition would be fairly straightforward in situations in which, for instance, a conflict is triggered by the capture of soldiers or by the sporadic and temporary military incursion of one State into an enemy State's territory. In these cases, the release of the soldiers or the end of the incursion would suffice to put an end to the armed conflict.

However, determining that an IAC has ended is likely to be far more complex where it was the result of active hostilities between the armed forces of two or more States. The proposition mentioned above would appear to be of limited utility in the face of a mere lull or cessation of hostilities. It would also seem to be of little use if, despite the end of active hostilities, the belligerent States continue to deploy troops on each other's borders, undertake military movements on their own territory for defensive or offensive purposes, or maintain a state of alert and mobilization of their troops.

Bearing in mind that the threshold for the existence of an IAC is fairly low, and that it would be impractical to treat every lull in the fighting as the end of it and each resumption as the start of a new one, the ICRC is of the opinion that hostilities must end with a degree of stability and permanence for an IAC to be deemed terminated. Thus, military operations short of active hostilities pitting one belligerent against another would still justify the continued existence of an IAC provided it can reasonably be considered that the hostilities are likely to resume in the near future due to ongoing military movements by the belligerents. Indeed, such a scenario would be insufficient to conclude that there is a general close of military operations. The notion “a general close of military operations” goes beyond the mere cessation of active hostilities, given that military operations of a belligerent nature do not necessarily imply the use of armed violence and that these may persist despite the absence of hostilities. In other words, it can be inferred that a general close of military operations includes not only the end of active hostilities but also the end of military movements of a bellicose nature, including those to reform, reorganize, or reconstitute. With the end of these movements, the likelihood of a resumption of hostilities can reasonably be ruled out.

End of a non-international armed conflict

As was discussed in the 2011 report on IHL and the challenges of contemporary armed conflicts, which was submitted to the 31st International Conference,Footnote ⁵ the factual scenarios of non-international armed conflicts are evolving and have become increasingly complex. In consequence, determining the end of IHL applicability to such conflicts has also become more difficult.

As is the case with IACs, international case law has not precisely identified when a situation of NIAC may be deemed to have come to an end. In the already mentioned seminal Tadić decision, the ICTY stated that, for the purposes of IHL applicability, a NIAC ceases when a “peaceful settlement” is reached.Footnote ⁶ As may be observed, this criterion does not provide sufficient practical guidance, and may even be interpreted as introducing a measure of formalism in a determination that should, first and foremost, be driven by facts on the ground. As a result, it is submitted that the notion “peaceful settlement” should be interpreted as a situation where a factual and lasting pacification of the NIAC has been achieved.

The requisite threshold of intensity will, admittedly, make the determination of the end of a NIAC even less straightforward than in an IAC scenario. There are, broadly speaking, two views on how to address this. One view is to rely on the intensity threshold required for NIACs (which is higher than that required for IACs, as explained above). Under this approach, it would be sufficient for the hostilities to fall below the threshold of “protracted armed violence” with a certain degree of permanence and stability. In other words, the legally relevant question would then be whether the threshold continues to be met. According to a second view, a NIAC only ceases to exist, and the applicability of IHL therefore comes to an end, when at least one of the opposing parties to the conflict has disappeared or no longer meets the level of organization required by IHL. A NIAC would also come to an end when the hostilities have ceased and there is no real risk of their resumption even though the level of organization of the parties is still met.

When considering these options, an important feature of NIACs should, however, be kept in mind. Such conflicts are often of a fluctuating nature, typified by temporary lulls in the armed violence or instability in the level of organization of the non-State party to the conflict. If these factors are automatically considered as signalling the end of a NIAC, this could lead to a premature conclusion as regards the end of applicability of IHL.

Taking this feature of NIACs into account, the closest one may come to the requirement of “a peaceful settlement” suggested by the relevant international case law is by waiting for the complete cessation of all hostilities – without real risk of resumption – before assuming that a NIAC has come to an end.Footnote ⁷

In the ICRC's practical experience, the cessation of all hostilities between the parties to the conflict and the absence of a real risk of their resumption – based on an overall assessment of the surrounding factual circumstances – have proven to provide the strongest and most reliable indicators that a NIAC has ended. The ICRC's practice has thus been to wait for the complete cessation of hostilities between the parties to a NIAC before assessing, based on the surrounding factual circumstances, whether there is a real risk of resumption of hostilities. If there is no such risk, the conclusion is drawn that the NIAC at issue has come to an end. The “risk of resumption” test helps ensure that the determination of the end of a NIAC is based not solely on the cessation of hostilities, which may be short-lived, but on an evaluation that related military operations of a hostile nature have also ended. In this way, the likelihood of a resumption of hostilities can reasonably be ruled out.

Beginning and end of occupation

A range of legal challenges raised by contemporary forms of occupation were at the core of an exploratory process undertaken by the ICRC on occupation and other forms of administration of foreign territory, which began in 2007 and concluded in 2012 with the publication of an ICRC report.Footnote ⁸ The purpose of this initiative was to analyse whether and to what extent the rules of occupation law are adequate to deal with the humanitarian and legal challenges arising in contemporary occupations, and whether they might need to be reinforced or clarified. The delineation of the notion of “occupation,” in particular its beginning and end, was one of the main issues addressed within this process.

Determining the existence of an occupation – which is a type of IAC – is complex given that the 1949 Geneva Conventions do not define the notion of occupation. It is, however, outlined in Article 42 of the Convention respecting the Laws and Customs of War on Land and its annex: Regulations concerning the Laws and Customs of War on Land of 1907 (hereafter 1907 Hague Regulations). Subsequent treaties, including the 1949 Geneva Conventions, have not altered this definition, which reads: “Territory is considered occupied when it is actually placed under the authority of the hostile army. The occupation extends only to the territory where such authority has been established and can be exercised.”

Apart from the need to determine the existence of an occupation based solely on the prevailing facts, the notion of occupation also requires an examination of the concept of “effective control,” which is at its core. While this concept is often used to characterize the notion of occupation, it should be noted that neither the 1949 Geneva Conventions nor the 1907 Hague Regulations contain a reference to it. In relation to occupation, “effective control” was developed in the legal discourse primarily to describe the circumstances and conditions for determining its existence.

It is self-evident that an occupation implies some degree of control by hostile troops over a foreign territory, or parts thereof, instead of by the territorial sovereign. Under IHL, it is the effectiveness of the control by foreign troops that triggers the application of the law of occupation. They will only be able to enforce their rights and duties under the law of occupation if they exercise effective control. In this regard, effective control is an essential concept, as it substantiates and specifies the notion of “authority,” which is at the core of the definition of occupation in Article 42 of the 1907 Hague Regulations.

On the basis of the 1907 Hague Regulations and their travaux préparatoires, scholarly literature, military manuals and judicial decisions, the ICRC has devised the following three conditions that need to be cumulatively met in order to establish a state of occupation within the meaning of IHL:

1. 1) The armed forces of a State are physically present in a foreign territory without the consent of the effective local government in place at the time of the invasion.

2. 2) The effective local government in place at the time of the invasion has been or can be rendered, substantially or completely, incapable of exerting its powers by virtue of the foreign forces' unconsented presence.

3. 3) The foreign forces are in a position to exercise authority instead of the local government over the concerned territory (or parts thereof).

Taken together, these constitute the so-called “effective-control test” which is used to determine whether a situation qualifies as an occupation for the purposes of IHL.

The end of an occupation may also be difficult to assess from a legal perspective. The legal classification of a given situation and the determination of when an occupation may be said to have ended can be complicated by several factors, such as progressive phase-out, partial withdrawal, retention of certain competences over previously occupied areas, or the maintenance of military presence based on questionable consent.

In principle, the effective-control test is equally applicable when establishing the end of occupation, meaning that the criteria to be met should generally mirror those used to determine the beginning of occupation, only in reverse. Thus, if any of the three conditions listed above ceases to exist, an occupation should be considered to have ended.

The ICRC considers, however, that in some specific and rather exceptional cases – in particular when foreign forces withdraw from occupied territory (or parts thereof) but retain key elements of authority or other important governmental functions usually performed by an occupying power – the law of occupation may continue to apply within the territorial and functional limits of such competences. Indeed, despite the lack of the physical presence of foreign forces in the territory concerned, the retained authority may amount to effective control for the purposes of the law of occupation and entail the continued application of the relevant provisions of this body of norms. This is referred to as the “functional approach” to the application of occupation law. This test will apply to the extent that the foreign forces still exercise, within all or part of the territory, governmental functions acquired when the occupation was undoubtedly established and ongoing.

The functional approach described above permits a more precise delineation of the legal framework applicable to situations in which it is difficult to determine, with certainty, whether an occupation has ended or not.

It may be argued that technological and military developments have made it possible to assert effective control over a foreign territory (or parts thereof) without a continuous foreign military presence in the concerned area. In such situations, it is important to take into account the extent of authority retained by the foreign forces rather than to focus exclusively on the means by which it is actually exercised. It should also be recognized that, in these circumstances, the geographical contiguity between belligerent States could facilitate the remote exercise of effective control. For instance, it may permit an occupying power that has relocated its troops outside the territory to reassert its full authority in a reasonably short period of time. The continued application of the relevant provisions of the law of occupation is all the more important in this scenario as these were specifically designed to regulate the sharing of authority – and the resulting assignment of responsibilities – between the belligerent States concerned.

The continued need to distinguish between the legal frameworks governing IHL and terrorism

The ICRC outlined its position on this issue in the preceding report on IHL and the challenges of contemporary armed conflicts submitted to the 31st International Conference. Given the current trends in counterterrorism, some aspects are worth recalling. This section aims to provide a brief reminder of the reasons for which, in the ICRC's view, the normative regimes governing armed conflict and terrorism should not be confused.

While the legal frameworks governing terrorism and IHL may have some common ground – IHL expressly prohibits most acts that are criminalized as “terrorist” in domestic legislation and international conventions dealing with terrorism – these two legal regimes remain fundamentally different. They have distinct rationales, objectives and structures.

A crucial difference is that, in legal terms, armed conflict is a situation in which certain acts of violence are considered lawful and others are unlawful, while any act of violence designated as “terrorist” is always unlawful. The ultimate aim of an armed conflict is to prevail over the enemy's armed forces. For this reason, the parties to a conflict are permitted, or at least are not prohibited from, attacking each other's military objectives or individuals not entitled to protection against direct attacks. Violence directed at those targets is not prohibited as a matter of IHL, regardless of whether it is inflicted by a State or a non-State party. Acts of violence directed against civilians and civilian objects are, by contrast, unlawful, as one of the main purposes of IHL is to spare them from the effects of hostilities. IHL thus regulates both lawful and unlawful acts of violence.

There is no such dichotomy in the norms governing acts of terrorism. The defining feature of any act that is legally classified as “terrorist,” whether under domestic or international law, is that it is always penalized as criminal. Thus, no act of violence legally designated as “terrorist” is, or can be, exempt from prosecution.

Another main difference between these legal frameworks is the principle of equality of belligerents, pursuant to which the parties to an armed conflict have the same rights and obligations under IHL (even if this is not the case under domestic law). This principle reflects the fact that IHL does not aim to determine the legitimacy of the cause pursued by the belligerents. Its goal, instead, is to ensure the equal protection of persons and objects affected by an armed conflict, irrespective of the lawfulness of the first resort to force. The legal framework governing acts of terrorism obviously does not contain a similar principle. In this context it is important to recall that, while IHL does foresee equal rights and obligations of belligerents in the conduct of hostilities and in the treatment of persons in their power, it does not confer legitimacy on non-State armed groups that are a party to a NIAC. Common Article 3 explicitly states that when parties to the conflict apply its provisions this “shall not affect the legal status of the Parties to the conflict.” Additional Protocol II contains a similar provision guaranteeing the sovereignty of States and their responsibility to maintain law and order, national unity and territorial integrity by all legitimate means (Article 3 of Additional Protocol II).

The above does not mean that some overlap cannot be created between the legal regimes governing IHL and terrorism. IHL prohibits both specific acts of terrorism committed in armed conflict and, as war crimes, a range of other acts of violence when committed against civilians or civilian objects. If States choose to additionally designate such acts as “terrorist” under international or domestic law, this will in effect duplicate their criminalization.

However, acts that are not prohibited by IHL – such as attacks against military objectives or against individuals not entitled to protection against direct attacks – should not be labelled “terrorist” at the international or domestic levels (although they remain subject to ordinary domestic criminalization where a NIAC is involved). Attacks against lawful targets constitute the very essence of an armed conflict and should not be legally defined as “terrorist” under another regime of law. To do so would imply that such acts must be subject to criminalization under that legal framework, therefore creating conflicting obligations of States at the international level. This would be contrary to the reality of armed conflicts and the rationale of IHL, which does not prohibit attacks against lawful targets.

Adding another layer of incrimination by designating acts that are not unlawful under IHL as “terrorist” may also discourage IHL compliance by non-State armed groups party to a NIAC. Any motivation they may have to fight in accordance with IHL would likely erode if, irrespective of the efforts they may undertake to comply with it, all of their actions are deemed unlawful. Furthermore, labelling acts that are lawful under IHL as “terrorist” is likely to render the implementation of Article 6(5) of Additional Protocol II – whose objective is to grant the broadest possible amnesty to persons having participated in the hostilities without having committed serious violations of IHL – more difficult. For obvious reasons, the prospect of an amnesty is diminished where even lawful acts of war have been qualified as acts of terrorism. This can ultimately prove to be an obstacle to peace negotiations and reconciliation efforts.

IHL, the so-called “war against terrorism” and the geographic scope of armed conflicts

As repeatedly asserted, the ICRC considers that, from a legal perspective, there is no such thing as a “war against terrorism.” With respect to the various armed conflicts and the numerous counterterrorism measures at the domestic and international levels, the ICRC adopts a case-by-case approach in order to analyse and legally classify the various situations of violence. In this sense, the fight against terrorism involves, apart from the use of force in certain instances, the use of other measures, such as intelligence gathering, financial sanctions and judicial cooperation.

When armed force is used, only the facts on the ground are relevant for determining the legal classification of a situation of violence. Some situations may be classified as an IAC, others as a NIAC, while various acts of violence may fall outside any armed conflict due to a lack of the requisite nexus.

With respect to the phenomenon of armed groups that are perceived as having a global reach, such as al-Qaeda or the Islamic State group, the ICRC does not share the view that an armed conflict of global dimensions is, or has been, taking place. This would require, in the first place, the existence of a “unitary” non-State party opposing one or more States. Based on available facts, there are not sufficient elements to consider the al-Qaeda “core” and its associated groups in other parts of the world as one and the same party within the meaning of IHL. The same reasoning also applies, for the time being, to the Islamic State group and affiliated groups.

In addition, as stated previously,Footnote ¹⁵ the ICRC does not share the view that the applicability of IHL spreads beyond the territory of the parties to the conflict in a way that would allow the targeting of individuals associated with armed groups around the world. The ICRC's position is that NIACs are confined to the territory of each party to an armed conflict. While such NIACs can spill over into neighbouring countries because of the continuity of hostilities, they cannot spread to third countries. The ICRC is of the view that the IHL criteria of intensity and organization required to constitute a NIAC would need to be fulfilled in the territory of each individual third State for the applicability of IHL to be triggered.

IHL and “foreign fighters”

The phenomenon of the so-called “foreign fighters” – nationals of one country who travel abroad to fight alongside a non-State armed group in the territory of another State – has increased exponentially over the past few years. In order to quell the threats emanating from foreign fighters, States – in particular within the framework of the UN Security Council – have taken a variety of measures, including the use of force, detention (on terrorism charges, among others), and travel bans.

While most of the measures taken to prevent individuals from joining non-State armed groups or to mitigate the threat they may pose upon return are of a law enforcement nature, the applicability of IHL, where appropriate, should not be overlooked. It may be observed that little attention has been paid to how IHL deals with the phenomenon of foreign fighters.

The concept of “foreign fighter” is not a term of art of IHL. The applicability of IHL to a situation of violence in which such fighters may be engaged depends on the facts on the ground and on the fulfilment of certain legal conditions stemming from the relevant norms of IHL, in particular common Articles 2 and 3. In other words, IHL will govern the actions of foreign fighters, as well as any measures taken in relation to them, when they have a nexus to an ongoing armed conflict.

Relevant IHL norms on the conduct of hostilities will govern the behaviour of foreign fighters, regardless of their nationality, in both IAC and NIAC. Foreign fighters are thus subject to the same IHL principles and rules that are binding on any other belligerent.

As far as detention is concerned, nationality will have an impact on the status of “protected persons” in IAC but not in NIAC. Under the Third Geneva Convention, nationality is irrelevant for determining whether a person qualifies as a combatant in an IAC, but may be important for determining whether a State will grant prisoner of war (POW) status to its own nationals captured fighting for a foreign army (State practice on this issue differs).

Nationality is a decisive criterion for determining whether a detained person will benefit from “protected person” status under the Fourth Geneva Convention. This treaty, by its express terms (Article 4), does not apply to persons of the nationality of the detaining State or to the nationals of neutral or co-belligerent States, except where there is no “normal” diplomatic representation between such States and the detaining State. In a situation of occupation, the nationals of neutral States, as well as the nationals of co-belligerent States, must be granted protected-person status, unless there is normal diplomatic representation between the co-belligerent State and the occupying power. In any case, if a foreign fighter is not granted POW or protected-person status under the Third or Fourth Geneva Convention, namely for reasons of nationality, he or she will still enjoy the “safety net” protections provided by Article 75 of Additional Protocol I, as a matter of treaty and/or customary law.

Nationality has no bearing on the status of foreign fighters in NIAC (as there is no POW or protected-person status as such in this type of armed conflict) or on the legal protections they will be owed upon capture. Hors de combat foreign fighters will thus be entitled to the guarantees of common Article 3 and of Additional Protocol II, when applicable, as well as to the safeguards of customary law norms.

Finally, foreign fighters are often assimilated to mercenaries. Under IHL, the notion of “mercenary” only exists in IAC and its only consequence is the loss of POW status.Footnote ¹⁶ This being said, foreign fighters may fulfil “mercenary” definitions contained in national legislations prohibiting mercenarism.

The ICRC's role in relation to foreign fighters is similar to that played with respect to any other persons captured and detained in relation to an armed conflict. If foreign fighters are detained in an IAC and fulfil the conditions for POW or protected-person status under the Third or Fourth Geneva Conventions, the ICRC must be granted access to them. If foreign fighters are detained within the framework of a NIAC, the ICRC can offer its humanitarian services to the detaining party and visit them upon the agreement of the relevant authorities.

Potential criminalization of humanitarian action

The potential criminalization of humanitarian action, as already described in further detail in the 2011 challenges report, remains an issue of concern for the ICRC and is therefore briefly reiterated here. The designation of a non-State armed group party to a NIAC as “terrorist” means that it is likely to be included in lists of proscribed terrorist organizations maintained by the UN, regional organizations and States. This may, in practice, have a chilling effect on the activities of humanitarian and other organizations carrying out assistance, protection and other activities in war zones. It has the potential to criminalize a range of humanitarian actors and their personnel, and may create obstacles to the funding of humanitarian activities. The prohibition of unqualified acts of “material support,” “services” and “assistance to” or “association with” terrorist organizations found in certain criminal laws could, in practice, result in the criminalization of the core activities of humanitarian organizations and their personnel that are endeavouring to meet the needs of victims of armed conflicts or situations of violence below the threshold of armed conflict. These activities could include: visits and material assistance to detainees suspected of, or condemned for, being members of a terrorist organization; facilitation of family visits to such detainees; first aid training; war surgery seminars; IHL dissemination to members of armed opposition groups included in terrorist lists; aid to meet the basic needs of the civilian population in areas controlled by armed groups associated with terrorism; and large-scale assistance activities for IDPs, where individuals associated with terrorism may be among the beneficiaries.

The potential criminalization of humanitarian engagement with non-State armed groups designated as “terrorist organizations” may be said to reflect a non-acceptance of the notion of neutral, independent and impartial humanitarian action, an approach which the ICRC strives to promote in its operational work in the field. The ICRC is permitted, and must in practice be free, to offer its services for the benefit of civilians and other persons affected by an armed conflict who find themselves in the power of, or in the area of control of, a non-State party.

In its 2011 report, the ICRC expressed the need for greater awareness by States of the need to harmonize policies and legal obligations in the humanitarian and counterterrorism realms in order to properly achieve the desired aim of both these realms. Its recommendations in this regard remain pertinent today. It therefore reiterates the following points:

• – Measures adopted by governments, whether internationally or nationally, aimed at criminally repressing acts of terrorism should be crafted so as to not impede humanitarian action. In particular, legislation creating criminal offences of “material support,” “services” and “assistance” to or “association” with persons or entities involved in terrorism should exclude from the ambit of such offences activities that are exclusively humanitarian and impartial in character, and are conducted without adverse distinction.

• – In respect of the ICRC in particular, it should be recognized that humanitarian engagement with non-State armed groups party to a NIAC is a task foreseen and expected from the ICRC under common Article 3, which allows the ICRC to offer its services to the parties to NIACs. Criminalization of humanitarian action would thus run counter to the letter and spirit of the 1949 Geneva Conventions. In other words, broad language prohibiting “services” or “support” to terrorism could make it impossible for the ICRC to fulfil its treaty-based (and statutory) mandate in contexts where non-State armed groups party to a NIAC are designated “terrorist organizations.”

The conditions for IHL applicability to multinational forces

Whether multinational forces can, as such, become a party to an armed conflict is a matter of much discussion. Recent peace operations have seen the development of legal constructs suggesting that the conditions triggering IHL applicability may differ when certain multinational forces intervene.Footnote ¹⁸ According to these views, IHL would not apply, would apply differently, or would apply only as a matter of policy to such forces.

In response to these views, it is to be noted that IHL does not preclude multinational forces from becoming a party to an armed conflict if the conditions for the applicability of its norms are met. The above views also ignore or do away with the longstanding distinction established in international law between ius in bello and ius ad bellum, which is firmly anchored in treaty law, as well as in domestic and international case law. By virtue of this distinction, the applicability of IHL to multinational forces, like to any other actors, depends exclusively on the circumstances prevailing on the ground, irrespective of the international mandate that may have been assigned to such forces or the term used to designate the party (or parties) potentially opposing them.

Given that multinational forces are more often than not deployed in conflict zones, it is essential to determine when they may be deemed to have become belligerents for the purposes of IHL. In this regard, some legal debates on IHL applicability to multinational forces have been characterized by recurrent attempts to raise the bar for the threshold of its applicability. It has been contended, in particular, that when multinational forces (in particular UN forces) are involved, a higher degree of intensity of violence should be required before an armed conflict may be said to exist.

The ICRC's view, which has been stated on various occasions, is that the criteria for determining whether multinational forces are involved in armed conflict are identical to those that will apply in any other similar situation, whether IACs or NIACs. Alternative positions would appear to lack a legal basis under IHL, as the “higher threshold approach” cannot be found in treaty law, and does not rest on general practice. Thus, the determination of IHL applicability to multinational forces should be based solely on the regular criteria for armed conflicts, stemming from the relevant norms of IHL, in particular common Articles 2 and 3.

Contemporary peace operations show that multinational forces often intervene in a pre-existing NIAC by providing support to the armed forces of a State in whose territory the conflict is occurring. This assistance has not often taken the form of full-fledged kinetic operations against a clearly identified enemy, but rather of sporadic use of force, logistical support, intelligence activities for the benefit of the territorial State or participation in the planning and coordination of military operations carried out by the armed forces of the territorial State.

This trend raises important legal questions: What is the legal status under IHL of multinational forces providing such support? Does IHL apply to them in this scenario? The complexity of the questions posed lies mainly in the fact that, in some cases, the support given by multinational forces does not by itself meet the threshold of intensity required for NIACs.

This situation has led to an examination of whether, even if the involvement of multinational forces does not per se meet the criterion of intensity required for NIACs, the nature of their engagement in a pre-existing NIAC could make them a party to that conflict.

The ICRC is of the view that it is not necessary to assess whether, on their own, the actions of multinational forces (or, generally, of individual States) fulfil the criteria for determining the existence of a NIAC, as these will have already been fulfilled by the pre-existing NIAC. Whether IHL will govern their operations in such a situation should only be determined by the nature of the support functions performed by the multinational forces. Therefore, a “support-based approach” consists in linking to IHL the actions of multinational forces that objectively form an integral part of the pre-existing NIAC.

Under such a support-based approach, not all forms of support will turn multinational forces into a party to a pre-existing NIAC. The decisive element would be the contribution made by such forces to the collective conduct of hostilities. A support-based approach clearly distinguishes between the provision of support that has a direct impact on the opposing party's ability to carry out military operations and more indirect forms of support, which would allow the beneficiary to build up its military capabilities. Only the former type of support would turn multinational forces into a party to a pre-existing NIAC.

According to a support-based approach, IHL would apply to multinational forces when the following conditions have been cumulatively met: (1) there is a pre-existing NIAC taking place on the territory in which multinational forces are called on to intervene; (2) actions related to the conduct of hostilities are undertaken by multinational forces in the context of the pre-existing conflict; (3) the military operations of multinational forces are carried out in support (as described above) of a party to the pre-existing conflict; and (4) the action in question is undertaken pursuant to an official decision by the troop-contributing country or the relevant organization to support a party involved in the pre-existing conflict.

The fulfilment of the above criteria should permit a clear determination of the existence of a genuine belligerent intentFootnote ¹⁹ on the part of multinational forces. The resulting situation would demonstrate that they are effectively involved in military operations or other hostile actions aimed at neutralizing the enemy's military personnel and assets, hampering its military operations or controlling parts of its territory.

In the ICRC's opinion the support-based approach helps clarify the contours of the notion of NIAC. It provides insight into how to interpret this notion in keeping with the logic of IHL, and in line with the imperative of not blurring the combatant/civilian distinction and of maintaining the principle of equality of belligerents.

Determining who is a party to an armed conflict

Once multinational forces have become involved in an armed conflict, it is important to identify who among the participants in a multinational operation should be considered a party to the conflict: the troop-contributing countries (TCCs)? The relevant international/regional organization (IO) under whose command and control the multinational forces operate? Or both? Little attention has been paid to these questions so far. They are nonetheless essential given the legal consequences involved.

IOs involved in peace operations all share one characteristic: they do not have armed forces of their own. In order to carry out such operations, IOs must rely on member States to place armed forces at their disposal. When they put troops at an IO's disposal, TCCs always retain some form of authority and control over their forces so that, even when they operate on behalf of the IO, they continue to simultaneously act as organs of their respective States. The dual status of armed forces involved in multinational operations conducted under the auspices of an IO – as organs of both the TCCs and the IO – considerably complicates the determination of who should be considered a party to the armed conflict.

In order to identify the parties, it is necessary to determine the entity – the IO and/or the TCCs – to which the acts of war carried out by multinational forces can be attributed. IHL is silent on the issue of attribution. It does not contain any specific criteria to attribute actions by multinational forces to a particular holder of international obligations. In the absence of such criteria in IHL, the general rules of international law on attribution will govern.

Under this body of international norms, the notion of control is key.Footnote ²⁰ In other words, determining who is a party to an armed conflict in the context of multinational operations requires an examination of the level of control exerted by the IO over the troops put at its disposal.

In order to answer this complex question, the command and control arrangements (“C2” in military parlance), and the corresponding levels of authority in force in multinational operations, must be analysed. There is no “one-size-fits-all” approach. The C2 structure varies from one operation to another and from one IO to another. It is undisputed, however, that TCCs do not delegate “full command” to the IOs involved, rather they generally only transfer “operational command” or “operational control.” Legally speaking, this means that an IO under whose auspices a multinational operation is conducted will usually have the requisite control – within the meaning of these terms under international law – over military operations conducted by the troops put at its disposal.

As regards multinational operations conducted under UN command and control, an analysis of relevant UN doctrine combined with a review of its practical application in various contexts shows that, despite the multiple caveats placed by TCCs and their potential interference in the UN chain of command, the UN generally exerts the requisite control over its military operations. Therefore, in multinational operations under UN C2, there is a presumption that only the UN mission, and not the TCCs (and even less the member States of the UN), should be considered a party to an armed conflict when UN forces are drawn into hostilities that may be classified as such.

The situation as regards multinational operations conducted by NATO is more complex. Owing to the very intricate and specific nature of the C2 architecture of NATO operations, it is submitted that, in principle, when NATO troops are engaged in armed conflict, it is not only the organization which is a party thereto. NATO C2 arrangements – as implemented for instance in Afghanistan or Libya – reveal that the involvement of TCCs at the strategic, operational and tactical levels is such that the relevant States clearly have the power and the capacity to influence and intervene at all levels and stages of NATO military operations. TCCs are so closely associated with the NATO C2 structure that it is almost impossible to discern whether it is NATO itself or the TCCs that have overall or effective control over military operations. In light of this, NATO operations should usually be attributed to the IO and the TCCs simultaneously. The logical legal consequence of this in terms of IHL is that both NATO and the TCCs (but not all NATO member States) should be considered parties to the armed conflict. In addition, since it is difficult in practice and in law to draw distinctions on the legal status under IHL of the States participating in such operations, the ICRC is of the view that carrying out military activities within a NATO operation, in particular if these form an integral part of the collective conduct of hostilities, confers the status of belligerent on the TCCs. In these circumstances, a presumption, albeit rebuttable, exists that States participating in a NATO operation that reaches the threshold of an armed conflict have – alongside NATO itself – the status of parties to the armed conflict.

The personal scope of IHL applicability in the context of multinational operations

The issue of the personal scope of IHL applicability is particularly important in the case of “multidimensional” or “integrated” multinational operations. The tasks of these operations may include not only military operations against designated enemies but also engagement in economic governance, civil administration, the rule of law, disarmament-demobilization-reintegration (DDR) efforts, political processes, the promotion/protection of human rights, and humanitarian assistance. In order to perform these tasks, “integrated” multinational operations employ a mix of military, police and civilian personnel. The implementation of the various objectives of a multinational mission that has become a party to an armed conflict will inevitably raise questions concerning the legal status under IHL of their various staff members.

The personnel of a multinational operation must be divided into different categories in order to evaluate the extent of IHL protection accorded to each. To this end, the situation of military, civilian and police personnel should be analysed separately.

Members of the military component of a multinational operation involved in an armed conflict must be distinguished from the rest of the mission's personnel. Once the military personnel become engaged in an armed conflict, they become “combatants” for the purpose of the principle of distinction. Thus, irrespective of their function within the military component, they lose their protection from attack as long as the multinational operation is a party to the armed conflict. Their status as lawful targets under IHL applies to the entire military contingent, even if the operation's forces are made up of units sent by different TCCs and even if they have different tasks within the mission. Their status under IHL is determined based on the classification of the situation, and in accordance with the corresponding norms of IHL.

Civilian personnel involved in economic/political governance, the promotion/protection of human rights or humanitarian assistance must be regarded as civilians for the purpose of IHL, irrespective of the fact that the multinational operation qualifies as a party to the armed conflict. The civilian component of a multinational operation must be distinguished from its military component. Civilian personnel will therefore remain protected from direct attack and benefit from the protection which IHL confers on civilians, unless and for such time as they directly participate in hostilities.

The situation with regard to the police component of a multinational operation may vary depending on its use by the operation's command. In the vast majority of cases, their tasks are confined to habitual law enforcement activities and have no direct connection with military operations that may be undertaken by the military component. As long as they are performing law enforcement tasks, police personnel must be regarded as civilians for the purpose of IHL. They will thus also benefit from the protection afforded to civilians, unless and for such time as they directly participate in hostilities.

In exceptional circumstances, the police personnel of a multinational operation (or more likely parts thereof) may be required – through either a formal or informal decision of an operation's command – to provide military support to the military component in operations against a non-State armed group party to a NIAC. Members of police units thus engaged would thereby effectively assume the functions of armed forces under the command of a party to the armed conflict. As a result, the police personnel of units that have been instructed to undertake combat action (but only such personnel) would lose their immunity against direct attack, until they leave their unit or are lastingly discharged from military operations undertaken by the military component.

Lastly, recent practice has shown that private military and security companies (PMSCs) may be hired to carry out tasks on behalf of TCCs or IOs involved in multinational operations. In this regard, an approach similar to that adopted with respect to the police component should be applied. If incorporated into multinational forces by being assigned a continuous combat function, PMSC personnel will no longer qualify as civilians and will become lawful targets under IHL for the duration of such an assignment.

Multinational forces and the obligation to respect and ensure respect for IHL

As mentioned above, contemporary multinational operations are often conducted in support of the armed forces of a “host” State fighting against a (or several) non-State armed group(s). Combined with the fact that they are conducted either by a coalition of States or by States that have put their troops at the disposal of an IO, multinational operations are situations in which the obligation to respect and ensure respect for IHL becomes all the more relevant. In the ICRC's view, this obligation is binding upon States involved in multinational operations, as well as on the IOs under whose auspices multinational operations are undertaken.

Participation in a multinational operation does not release States from their obligation under Article 1 common to the 1949 Geneva Conventions to respect and ensure respect for IHL. To the extent that they always retain some authority over their national contingents, troop-contributing countries must continue to ensure that their national contingents respect IHL. They may fulfil the “internal” prong of the obligation to ensure respect, in particular, by seeing to it that their troops are adequately trained, equipped and instructed, and by exercising disciplinary and judiciary powers over them.

Furthermore, the complexity of multinational operations does not diminish the validity of the other, “external” prong of the obligation contained in common Article 1. According to this obligation, States must ensure that IHL is respected by others – be they States, IOs or non-State armed groups – involved in an armed conflict. This obligation requires that States not only refrain from encouraging, aiding or assisting violations of IHL (which may require opting out of a specific operation if there is an expectation that it may violate IHL), but also exert their influence to the degree possible to induce belligerents to comply with IHL. It is, however, acknowledged that this prong of the obligation to ensure respect for IHL, i.e. to exert their influence, is an obligation of means to be exercised with due diligence. The exact scope of this obligation will depend on the prevailing circumstances of each case and on the resources available to the bearer of the obligation, in particular its capacity to influence the (other) belligerents.

It is likewise submitted that the “special relationship” and the close military ties that exist between States and IOs involved in a multinational operation place them in a unique position to influence coalition partners and/or the supported party in order to persuade the latter to better respect IHL.

Multinational operations may be said to constitute a platform facilitating the implementation of the obligation to ensure respect for IHL by others. The ICRC has often insisted on the importance of ensuring respect for IHL in the context of multinational operations and has regularly reminded – confidentially or publicly, individually or collectively – TCCs and IOs of their obligation under common Article 1 or equivalent customary international law.

The application of the rules of proportionality in attack and precautions to military medical personnel and objects

Military medical personnel often have to work, and military medical objects must often be located, in the vicinity of the fighting, especially when providing emergency medical care, including first aid. There is evidently a particular need to ensure the protection of military medical personnel and objects against incidental harm (which is likely to be heightened in situations of urban warfare). A controversy nevertheless exists over whether such protection must be ensured in attacks against military objectives located in the proximity of military medical personnel and objects or when their movements bring them in proximity of military objectives.

Some have argued that military wounded and sick, as well as military medical personnel and objects, are not protected by the rules of proportionality in attack and precautions because the relevant customary rules, as reflected in Additional Protocol I, only refer to incidental civilian harm. Pursuant to this view, military wounded and sick, and military medical personnel and objects are excluded from the protective ambit that the relevant norms aim to provide, as they are not of a civilian nature.

It is submitted that this position is untenable. In practice, this could result in a decrease in the emergency medical care that is provided in proximity to military objectives, as military medical personnel and objects would not only de facto run the risk of being incidentally harmed but would also not enjoy any legal protection from such risk.

As a matter of law, this proposition is, first, incompatible with the stringent nature of the obligation to respect and protect military medical personnel and objects, as well as with the object and purpose of their specific protection. This obligation, which applies in all circumstances (unless military medical personnel and objects commit, or are used to commit, acts harmful to the enemy), means that they must not be attacked or harmed in any way, and that everything feasible must be done to spare them in the conduct of hostilities. Moreover, the very concept of specific protection implies a protection that is elevated in relation to that which is generally guaranteed to civilians and civilian objects. This is evidenced by the right to use the protective red cross, red crescent or red crystal emblem. To suggest a lesser protection for military medical personnel and objects than that accorded to civilians and civilian objects would thus run counter to the very concept of specific protection.

Second, a careful reading of the definition of military objectives suggests that military medical objects are to be considered civilian objects under the rules on the conduct of hostilities. This is because military objectives are limited to those that make an effective contribution to military action and whose destruction, capture or neutralization, in the circumstances ruling at the time, offers a definite military advantage. Military medical facilities and transports do not fulfil these cumulative conditions (at least as long as they are not used to commit acts harmful to the enemy, outside of their humanitarian function). Given that under IHL civilian objects are all those that are not military objectives, military medical objects must be considered to be civilian objects.

Third, the proposition that military medical personnel and objects do not enjoy protection under the rules of proportionality in attack and precautions, while civilian medical personnel and objects do, runs counter to the fundamental purpose of the relevant rules of Additional Protocols I and II, which specifically envisage uniform protections for these categories of persons and objects.

Finally, the military manuals of a number of States support the inclusion of protected persons and objects, other than civilians and civilian objects, in the assessment of incidental harm that must be undertaken pursuant to the rules of proportionality in attack and precautions.

The scope of the notion of “acts harmful to the enemy”

Under IHL, medical personnel, facilities and transports will lose their specific protection upon the commission of an “act harmful to the enemy, outside their humanitarian function.” This may obviously have serious consequences for the continued delivery of medical care to the wounded and sick, as well as for the security of medical personnel and objects that were not involved in the act(s) at issue. Confidence may be lost in the exclusively medical nature of medical personnel and objects as such, and lead, overall, to less of a willingness to accord them respect and protection. Despite these ramifications, IHL does not define the concept of “acts harmful to the enemy,” nor the precise consequences of a loss of specific protection or how long this lasts.

IHL treaties do not list “acts harmful to the enemy” but they enumerate certain factual scenarios that do not constitute this type of acts, including when medical personnel are equipped with light individual weapons for their own defence or that of the wounded and sick in their charge.Footnote ²⁸ Examples of acts that would generally be recognized as “harmful to the enemy” under customary IHL are the use of medical facilities for sheltering persons directly participating in hostilities or for storing arms and ammunition (other than small arms and ammunition temporarily found and taken from the wounded and sick, and not yet handed over to the competent authorities). Other instances would be: the use of medical facilities as military observation posts or to physically shield military action; and the use of medical transports for conveying healthy troops, arms or munitions, or for the collection and transmission of information of military value.

When medical objects are being used for the commission of “acts harmful to the enemy, outside their humanitarian function,” this may have an impact both on their entitlement to be respected on the one hand and, separately, on their entitlement to be protected on the other hand. When it comes to their entitlement to the latter, their being used for the commission of such an act may dispense the enemy from the obligation, otherwise applicable to it, to make sure that third parties respect medical objects. When it comes to the loss of their entitlement to be respected, a question that may be posed is whether the fact that they are used for the commission of “acts harmful to the enemy” automatically turns them into military objectives (meaning that they lose protection against direct attack) or whether there are “acts harmful to the enemy” that would not necessarily turn medical objects into military objectives. In such cases, loss of protection does not permit a direct attack. It is submitted that not all forms of “acts harmful to the enemy” would make an effective contribution to military action and an attack directed against them would not, in the circumstances ruling at the time, offer a definite military advantage. The failure to fulfil either of these requirements implies that such medical objects may not be considered to have become military objectives (see Article 52(2) of Additional Protocol I and its customary equivalent). In such cases, responses to such harmful acts would have to be through measures short of attack, such as seizure (which, when exercised vis-à-vis medical objects, is regulated by IHL to ensure the continued care of the wounded and sick who will be affected by this measure). In most cases, however, it would be hard to conceive of circumstances in which the commission of an “act harmful to the enemy” outside its humanitarian function would not transform a medical object into a military objective.

It should, nevertheless, be observed that in consultations with military experts as part of the Health Care in Danger project mentioned above, a recommendation was made, not necessarily based on legal considerations, that kinetic strikes against a medical facility that has lost protection should be considered a last resort, and that options other than launching a direct attack on such a facility should be contemplated.

In terms of medical personnel, controversy has arisen as to whether “acts harmful to the enemy” are the same as, or broader in material scope than, “direct participation in hostilities” by civilians. Some, including the ICRC, support the view that the notion of “acts harmful to the enemy” is broader because certain acts that are generally considered to be “harmful to the enemy” may not amount to “direct participation in hostilities.” If the “acts harmful to the enemy” do not amount to direct participation in hostilities, the medical personnel may lose their entitlement to be protected. When it comes to the implications this has for their entitlement to be respected, such acts do not necessarily render the personnel liable to direct attack. This would only be the case if these acts equally qualify as acts of “direct participation in hostilities.”

Challenges in safeguarding essential civilian infrastructure against cyber attacks

There has been increasing concern in recent years about safeguarding essential civilian infrastructure against cyber attacks, and calls to protect it from hostile cyber operations, including through the development of norms of acceptable behaviour in cyberspace. In this context, it should be noted that cyber operations amounting to an attack under IHLFootnote ⁴⁶ and directed at essential civilian infrastructure in armed conflict already constitute violations of IHL, unless such infrastructure is simultaneously used for military purposes in a way that turns it into a military objective. For example, drinking water and electricity networks that serve the civilian population, public health infrastructure and banks are first and foremost civilian objects. Furthermore, water systems, in particular, enjoy special protection as objects indispensable to the survival of the population. Similarly, dams and nuclear electricity plants are usually protected against direct attack because they do not constitute military objectives. Even if they were to become military objectives in particular circumstances, IHL prohibits their attack or at least requires that particular care be taken to avoid the release of dangerous forces and consequent severe losses among the civilian population. This is not to deny that new norms might be useful or even needed, but rather to stress that if they are developed they should build upon and strengthen what already exists.

The extent of protection based on the general rules on the conduct of hostilities, as contained in treaty or customary IHL, will depend on how certain notions and concepts are interpreted by States.

By way of example, the manner in which the notion of cyber “attack” is defined under the rules governing the conduct of hostilities (see Article 49 of Additional Protocol I) will greatly influence the protection that IHL affords to essential civilian infrastructure. The debate centres around the notion of loss of functionality of an object, given that in cyberspace it is possible to render objects dysfunctional without physically damaging them.

One view is to consider that cyber attacks are only those operations that cause violence to persons or physical damage to objects. A second approach is to make the analysis dependent on the action necessary to restore the functionality of the object, network or system. A third approach is to focus on the effects that the operation has on the functionality of the object.

It is submitted that all operations expected to cause death, injury or physical damage constitute attacks, including when such harm is due to the foreseeable indirect or reverberating effects of an attack, such as the death of patients in intensive-care units caused by a cyber attack against the electricity network that then cuts the hospital electricity supply.

The ICRC also considers that an operation designed to disable an object – for example a computer or a computer network – constitutes an attack under the rules on the conduct of hostilities, whether or not the object is disabled through kinetic or cyber means.Footnote ⁴⁷ Indeed, the reference to “neutralization” in the definition of military objective (Article 52 of Additional Protocol I) would be superfluous if an operation aimed at impairing the functionality of an object (i.e. its neutralization) would not constitute an attack. Furthermore, an overly restrictive understanding of the notion of attack would be difficult to reconcile with the object and purpose of the rules on the conduct of hostilities, which is to ensure the protection of the civilian population and civilian objects against the effects of hostilities. Indeed, under such a restrictive understanding, a cyber operation that is directed at making a civilian network (electricity, banking, communications or other network) dysfunctional, or risks causing this incidentally, might not be covered by the IHL prohibition of directing attacks against civilian objects, the prohibitions of indiscriminate or disproportionate attacks and the principle of precautions in attack, despite the potentially severe consequences of such operations for the civilian population.

Based on the current understanding of the IHL notion of “attack” in kinetic operations, it is, however, evident that not all cyber operations would constitute attacks. First, the concept of attack does not include espionage.Footnote ⁴⁸ Second, the rules on the conduct of hostilities do not prohibit all operations that interfere with civilian communication systems. For instance, the jamming of radio communications or television broadcasts has not traditionally been considered an attack in the sense of IHL.Footnote ⁴⁹

More generally, in order to differentiate between operations that amount to attacks and those that do not, it has been suggested that the criterion of “inconvenience” should be relied upon when it comes to the effects of a particular operation. However, what is covered by “inconvenience” is not defined and this terminology is not used in IHL.

Even cyber operations that would constitute “military operations” without amounting to “attacks” per se are governed by the principle of distinction. According to this principle, there is an obligation to distinguish at all times between civilians and civilian objects on the one hand, and military objectives on the other, and to take constant care in the conduct of military operations to spare the former.Footnote ⁵⁰

Challenges in protecting cyber infrastructure on which essential civilian infrastructure relies

In order to protect essential civilian infrastructure that relies on cyberspace, it is also crucial to protect the infrastructure of cyberspace itself. The challenge lies, however, in the interconnectedness of civilian and military networks. Most military networks rely on civilian cyber infrastructure, such as undersea fibre-optic cables, satellites, routers or nodes. Conversely, civilian vehicles, shipping, and air traffic controls are increasingly equipped with navigation systems that rely on global positioning system (GPS) satellites, which are also used by the military. Civilian logistical supply chains (for food and medical supplies) and other businesses use the same web and communication networks through which some military communications pass. Thus, it is to a large extent impossible to differentiate between purely civilian and purely military cyber infrastructures.

The traditional understanding of the notion of military objective is that when a particular object is used for both civilian and military purposes (so-called “dual-use objects”), it becomes a military objective (except for the separable parts thereof). A strict application of this understanding could lead to the conclusion that many objects forming part of the cyberspace infrastructure would constitute military objectives and would not be protected against attack, whether cyber or kinetic. This would be a matter of serious concern because of the ensuing impact that such a loss of protection could have in terms of disruption of the ever-increasing concomitant civilian usage of cyber space. However, because cyberspace is designed with a high level of redundancy, one of its characteristics is the ability to immediately reroute data traffic. This inbuilt resilience needs to be taken into account when assessing whether the target's destruction or neutralization would actually offer a definite military advantage in the circumstances ruling at the time, as required by the second prong of the definition of a military objective.

Even if certain parts of the cyberspace infrastructure on which essential civilian functions rely were to become lawful targets, any attack would remain governed by the prohibition of indiscriminate attacks and the rules of proportionality and precautions in attack. Assessing the expected incidental harm of any planned operation is of critical importance for the application of both principles. Precisely because civilian and military networks are so interconnected, incidental civilian harm must be expected in most cases, and all reasonably foreseeable harm must be taken into account, including incidental harm indirectly caused by the reverberating effects of the attack. For example, attacks against root servers or undersea cables would raise concerns under the prohibition of indiscriminate attacks because of the difficulty of limiting the effects of such attacks, as required by IHL. In this context, the protection afforded by the law of neutrality would also need to be considered.

Challenges in protecting essential civilian data

There is also increasing concern about safeguarding essential civilian data. With regard to data belonging to certain categories of objects that enjoy specific protection under IHL, the protective rules are comprehensive. For example, the obligation to respect and protect medical facilities must be understood as extending to medical data belonging to those facilities. However, it would be important to clarify the extent to which civilian data that does not benefit from such specific protection, such as social security data, tax records, bank accounts, companies' client files or election lists or records, is already protected by the existing general rules on the conduct of hostilities. Deleting or tampering with such data could quickly bring government services and private businesses to a complete standstill, and could cause more harm to civilians than the destruction of physical objects. The conclusion that this type of operation would not be prohibited by IHL in today's ever more cyber-reliant world – either because deleting or tampering with such data would not constitute an attack in the sense of IHL or because such data would not be seen as an object that would bring into operation the prohibition of attacks on civilian objects – seems difficult to reconcile with the object and purpose of this body of norms.

The importance of feasible measures to protect civilians and civilian objects against the effects of hostilities

IHL also requires that the parties to a conflict take all feasible measures to protect civilians and civilian objects under their control against the effects of hostilities. This obligation has to be implemented already in peacetime, especially with regard to fixed installations. While cyberspace is a virtual global domain, it would appear that the obligation to take precautions against the effects of attacks extends at least to the physical infrastructure of cyberspace (and to objects whose functioning depends on that infrastructure) located in a State's territory, or in any territory that may be occupied by a party to the conflict.

This raises the question of the measures that States must take to protect the civilian population under their control from the danger of cyber operations, including in the case of a cyber operation against the State's essential infrastructure. Measures that could be considered include: segregating military from civilian cyber infrastructure and networks; segregating computer systems on which essential civilian infrastructure depends from the internet; backing up important civilian data; using antivirus measures; and making advance arrangements to ensure the timely repair of important computer systems against foreseeable kinds of cyber attacks. Other avenues that could be explored – requiring international cooperation and, probably, innovative solutions to technical problems – would be to work on the identification in cyberspace of the cyber infrastructure and networks serving specially protected objects like hospitals, or to draw inspiration from the protection attached to demilitarized or protected zones and to assess whether such an approach could usefully be transposed into the cyber realm.

The importance of the legal review of cyber capabilities

These and other issues underscore why it is important that States that may develop or acquire cyber-warfare capacities, whether for offensive or defensive purposes, assess their lawfulness under IHL. Legal review, as specifically required by Article 36 of Additional Protocol I, is essential to ensuring that armed forces and other government agencies that may potentially resort to cyber operations in an armed conflict are able to abide by their obligations under international law. However, the legal review of cyber weapons, means and methods of warfare may present a number of challenges. Military cyber capabilities might be less standardized than kinetic weapons, especially if designed for a specific operation; furthermore, they are likely to be subject to constant adaptation, including to respond to the software security upgrades that a potential target will undergo.

In sum, the ICRC believes that clarifying how IHL applies to cyber warfare would help shed light on whether its rules are sufficiently clear in view of the specific characteristics and foreseeable humanitarian impact of cyber warfare. Given that this type of warfare poses novel questions, there may also be a need to develop IHL as technologies evolve or as the human cost of cyber warfare becomes better understood.

Definitions

There is no internationally agreed definition of autonomous weapon systems,Footnote ⁵¹ but common to various proposed definitions is the notion of a weapon system that can independently select and attack targets. On this basis, the ICRC has proposed that “autonomous weapon systems” is an umbrella term that would encompass any type of weapon systems, whether operating in the air, on land or at sea, with autonomy in its “critical functions,” meaning a weapon that can select (i.e. search for or detect, identify, track, select) and attack (i.e. use force against, neutralize, damage or destroy) targets without human intervention. After initial activation, it is the weapon system itself – using its sensors, programming and weapon(s) – that takes on the targeting processes and actions that are ordinarily controlled directly by humans.

At a fundamental level, it is autonomy in the critical functions that distinguishes autonomous weapon systems from all other weapon systems, including armed drones in which critical functions are controlled remotely by a human operator.

Some weapon systems in use today have autonomy in their critical functions. These include air and missile defence weapon systems, ground vehicle “active protection” weapon systems, and border or perimeter weapon systems (sometimes called “sentry guns”), as well as loitering munitions and armed underwater vehicles. Many of these weapon systems have autonomous “modes,” meaning they can be “switched on” to operate autonomously for fixed periods of time. Most tend to be highly constrained in the tasks they are used for (e.g. defensive rather than offensive operations), the types of targets they attack (vehicles and other objects rather than personnel), and the circumstances in which they are used (in simple, relatively predictable and constrained environments rather than complex, unpredictable environments). Importantly, it seems that most of these existing weapons are overseen in real time by a human operator.

However, future autonomous weapon systems might be given more freedom of action to determine their targets, to operate outside tightly constrained spatial and temporal limits, and to react to rapidly changing circumstances. The current pace of technological developments lends urgency to the consideration of the legal, humanitarian and ethical implications of these weapons.

Compliance of autonomous weapon systems with IHL

Based on the state of current and foreseeable robotics technology, ensuring that autonomous weapon systems can be used in compliance with IHL will pose a formidable technological challenge as these weapons are assigned more complex tasks and deployed in more dynamic environments than has been the case until now.

Key challenges include whether the weapon system would be capable of autonomously distinguishing military objectives from civilian objects, combatants from civilians, and active combatants from persons hors de combat. Another key challenge is whether a weapon could be programmed to sense and weigh up the many contextual factors and variables required to determine whether the attack may be expected to cause incidental civilian casualties and damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated, as required by the rule of proportionality. Likewise, the ability to programme a weapon to cancel or suspend an attack if it becomes apparent that the target is not a military objective or is subject to special protection, or that the attack may be expected to violate the rule of proportionality, as required by the rules on precautions in attack, appears a formidable challenge.

Thus, for autonomous weapon systems intended for use in contexts where they are likely to encounter protected persons or objects, there are serious doubts as to whether it is technically possible to programme them to carry out the complex, context-dependent assessments required by the IHL rules of distinction, proportionality and precautions in attack. These are inherently qualitative assessments in which unique human reasoning and judgement will continue to be required.

In view of these challenges, there are serious doubts about the capability of developing and using autonomous weapon systems that would comply with IHL in all but the narrowest of scenarios and the simplest of environments, at least for the foreseeable future. In this respect, it seems evident that overall human control or oversight over the selection and attack of targets will continue to be required to ensure respect for IHL. The kind and degree of human control or oversight required to ensure compliance of an autonomous weapon system with IHL will depend on the type of autonomous weapon system, the tasks it is designed to carry out, the environment in which it is intended to be used, and the types of targets it is programmed to attack, among other factors.

Legal review of autonomous weapon systems

The above challenges will need to be carefully considered by States when carrying out legal reviews of any autonomous weapon system they develop or acquire, as required by IHL. As with all weapons, the lawfulness of a weapon with autonomy in its critical functions depends on its specific characteristics, and whether, given those characteristics, it can be employed in conformity with the rules of IHL in all of the circumstances in which it is intended and expected to be used. The ability to carry out such a review entails fully understanding the weapon's capabilities and foreseeing its effects, notably through testing. Yet foreseeing such effects will become increasingly difficult if autonomous weapon systems are increasingly able to determine their own actions in complex environments.

Predictability about the actions of an autonomous weapon system in the context in which it is to be deployed must be sufficiently high to allow an accurate legal review. Indeed, deploying a weapon system whose effects are wholly or partially unpredictable would create a significant risk that IHL will not be respected. In this regard, a key question for the reviewer is how to evaluate and mitigate the risks of using the weapon if its performance is unpredictable. The risks may be too high to allow the weapon's use; otherwise, mitigating the risks may require appropriate levels of human control over the critical functions of the weapon system, consequently limiting or even obviating the weapon's autonomy.

An additional challenge for reviewing the legality of an autonomous weapon system is the absence of standard methods and protocols for testing these weapons. This too may affect the accuracy of the legal review.

Accountability for the use of autonomous weapon systems

Some have raised concerns that the loss of human control over autonomous weapon systems may lead to an “accountability gap” in case of violations of IHL. Others are of the view that no such gap would ever exist as there will always be a human involved in the decision to deploy the weapon to whom responsibility could be attributed. Still, it is unclear how responsibility could be attributed in relation to unpredictable “acts” of autonomous weapons.

For instance, under IHL and international criminal law, the lack of control over, or the unpredictability of, an autonomous weapon system could make it difficult to find individuals involved in the programming and deployment of the weapon liable for serious violations of IHL. They may not have the knowledge or intent required for such a finding, owing to the fact that the machine takes the targeting decisions. Moreover, programmers might not have knowledge of the concrete situations in which at a later stage the weapon would be deployed and in which IHL violations would occur. On the other hand, a programmer who intentionally programmes an autonomous weapon to commit war crimes would certainly be criminally liable. Likewise, a commander would be liable for deciding to use autonomous weapon systems in an unlawful manner, for example deploying in a populated area an anti-personnel autonomous weapon that is incapable of distinguishing civilians from combatants. In addition, a commander who knowingly decides to deploy an autonomous weapon whose performance and effects he/she cannot predict may be held criminally responsible for any serious violations of IHL that ensue, to the extent that his/her decision to deploy the weapon is deemed reckless under the circumstances.

Under the law of State responsibility, in addition to accountability for violations of IHL committed by its armed forces, a State could be held liable for violations of IHL caused by an autonomous weapon system that it has not, or has inadequately, tested or reviewed prior to deployment. Under the laws of product liability, manufacturers and programmers could also be held accountable for errors in programming or for the malfunction of an autonomous weapon system.

Autonomous weapon systems under the dictates of public conscience

As autonomy increases in the critical functions of weapon systems, a point is reached where humans are so far removed in time and space from the selection and attack of targets that human decision-making regarding the use of force is substituted with machine decision-making. This raises profound moral and societal questions about the role and responsibility of humans in the use of force and the taking of human life.

The fundamental question at the heart of concerns about autonomous weapon systems, irrespective of their compliance with IHL, is whether the principles of humanity and the dictates of public conscienceFootnote ⁵² would allow machines to make life-and-death decisions in armed conflict without human involvement. The debates of recent years among States, experts, civil society and the public have shown that there is a sense of deep discomfort with the idea of any weapon system that places the use of force beyond human control.

The way forward: Meaningful human control over the use of force in armed conflict

Discussions among government experts in the CCW in 2014 and 2015 have shown that there is broad agreement that meaningful, appropriate or effective human control over the critical functions of weapon systems must be retained, whether for legal, ethical and/or policy reasons. In view of the rapid advances in military robotics, there is now a need for States to take concrete steps to prevent the loss of human control over the use of force in armed conflict.

Experience with existing autonomous weapon systems can provide guidance on where the limits of autonomy in the critical functions of weapon systems should lie. In this respect, the ICRC encourages States that have deployed, or are currently developing, autonomous weapon systems to share their experience of how they are ensuring that these can be used in compliance with IHL, and of the limits and conditions they are fixing on the use of these weapons, including the required level of human control, be it for legal, ethical and/or policy reasons.

A pattern of increasing harm in contemporary armed conflicts

Hostilities are increasingly being conducted in population centres, thereby exposing civilians to heightened risks of harm. This trend of contemporary armed conflicts is only likely to continue with growing urbanization. It is compounded by the fact that belligerents often avoid facing their enemy in the open, intermingling instead with the civilian population. Yet, armed conflicts often continue to be waged with weapon systems originally designed for use in open battlefields. There is generally no cause for concern when such weapons are used in open battlefields, but when they are used against military objectives located in populated areas they are prone to indiscriminate effects, often with devastating consequences for the civilian population.

Indeed, warfare in populated areas using explosive weapons that have a wide impact area exacts a terrible toll on civilians. Recent armed conflicts have confirmed that the use of such weapons is a major cause of civilian death and injury and destruction and damage of civilian residences and critical civilian infrastructure, with consequent disruption to essential services, such as health care and water distribution, and displacement of the civilian population. In terms of effects on people's health, these are not limited to death, physical injury and long-term disability, but also include the long-term impact on mental well-being. The use of explosive weapons in populated areas also affects the ability of health-care facilities and services to operate, to cope with the influx of numerous wounded people and the particular injuries they present, and to provide adequate care. The foregoing effects are accentuated in contexts where the use of explosive weapons is protracted, with the consequent decline of essential services over time and serious risks for public health.

The ICRC continues to witness these effects first-hand as it assists the victims of armed conflicts involving the use of explosive weapons in populated areas. The ICRC has raised its concerns with the parties to such armed conflicts as part of its bilateral and confidential dialogue on the conduct of hostilities. Since 2009, it has also been publicly expressing its concerns regarding explosive weapons in populated areas.

In its report submitted to the 31st International Conference in 2011, the ICRC stated that “due to the significant likelihood of indiscriminate effects and despite the absence of an express legal prohibition for specific types of weapons, the ICRC considers that explosive weapons with a wide impact area should be avoided in densely populated areas.”Footnote ⁵³

In 2013, the Movement as a whole called upon States to “strengthen the protection of civilians from the indiscriminate use and effects of explosive weapons, including through the rigorous application of existing rules of international humanitarian law, and to avoid using explosive weapons with a wide impact area in densely populated areas.”Footnote ⁵⁴

In parallel, the UN secretary-general has, consistently since 2009, drawn the attention of UN member States to the need to strengthen the protection of civilians in view of the humanitarian impact of the use of explosive weapons in populated areas, as have UN agencies and non-governmental organizations. A growing number of States are also acknowledging the humanitarian concerns raised by this phenomenon.

The ICRC continues to document the impact on civilians of the use of these weapons in a range of armed conflicts. It has also been looking more closely at the technical characteristics of certain types of explosive weapons that may foreseeably have wide-area effects when used in populated areas. It has been engaging in dialogue with selected armed forces to gain a better understanding of existing military policy and practice relevant to the choice and use of explosive weapons in populated areas. It has also deepened its analysis of the IHL rules that frame the use of explosive weapons in populated areas. To help shape debates and its own views on these issues, the ICRC convened a meeting of government and independent experts in February 2015.Footnote ⁵⁵ The ICRC's current observations and views are outlined below.

Framing the issue: The use of “explosive weapons” with a “wide impact area” in “densely populated areas”

Explosive weapons, that is weapons that injure or damage by means of explosive force,Footnote ⁵⁶ may have a “wide impact area” – or “wide-area effects” – when used in populated areas due to:

• ◦ the large destructive radius of the individual munition used, i.e. its large blast and fragmentation range or effect (such as large bombs, large-calibre mortars and rockets, large guided missiles, and heavy artillery projectiles);

• ◦ the lack of accuracy of the delivery system (typically indirect fire weapons, such as mortars, rockets, and artillery (especially when using unguided munitions) and unguided air-delivered bombs); or

• ◦ the weapon system being designed to deliver multiple munitions over a wide area (such as multiple rocket-launcher systems).

In this respect, the issue of explosive weapons in populated areas concerns not one single weapon, but a range of different conventional weapon systems, and consideration of the circumstances of their use, including the typical vulnerabilities of civilians living in populated areas, is needed.

Insofar as improvised explosive devices (IEDs) may fall into one of the above three general categories of explosive weapons, they are also a cause for concern when used in populated areas.

The terms “densely populated areas” and “populated areas” should be understood as synonymous with “concentration of civilians,” the latter being the only of these terms defined by IHL treaties, as in “a city, town, village or other area containing a similar concentration of civilians or civilian objects.”Footnote ⁵⁷

Direct attacks against civilians or civilian objects are beyond the focus of the present discussion on explosive weapons in populated areas, as such attacks are clearly unlawful under IHL regardless of the types of weapons used.

In sum, the challenges relating to “explosive weapons in populated areas” discussed here refer to the use of explosive weapons that, due to their wide-area effects, may foreseeably cause significant civilian casualties and/or damage to civilian objects, as well as long-term harm to the civilian population, when used against a military objective located in a concentration of civilians.

A significant likelihood of indiscriminate effects

In view of the humanitarian consequences outlined above, and as previously stated, the ICRC is of the view that explosive weapons with a wide impact area should not be used in densely populated areas due to the significant likelihood of indiscriminate effects, meaning that their use against military objectives located in populated areas is likely to fall foul of the IHL rules prohibiting indiscriminate and disproportionate attacks.

Indiscriminate attacks are those of a nature to strike military objectives and civilians or civilian objects without distinction, notably because they employ means or methods of warfare that cannot be directed at a specific military objective or the effects of which cannot be limited as required by IHL.Footnote ⁵⁸ Disproportionate attacks and area bombardment are treated as particular forms of indiscriminate attacks. The rule of proportionality prohibits attacks “which may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated.”Footnote ⁵⁹ Area bombardment is defined as “an attack by bombardment by any methods or means which treats as a single military objective a number of clearly separated and distinct military objectives located in a city, town, village or other area containing a similar concentration of civilians or civilian objects.”Footnote ⁶⁰ The foregoing rules must be respected by the parties to an armed conflict in all circumstances,Footnote ⁶¹ even if alternative, more discriminate weapons or tactics are not available to them.

In addition to these obligations, the IHL rule of precautions in attack requires the parties to an armed conflict, in the conduct of their military operations, to take constant care to spare the civilian population, individual civilians and civilian objects.Footnote ⁶² This rule notably requires “those who plan or decide upon an attack” to take “all feasible precautions in the choice of means and methods of attack with a view to avoiding, and in any event to minimizing, incidental loss of civilian life, injury to civilians and damage to civilian objects.”Footnote ⁶³ When conducting hostilities in populated areas, the rule of precautions may require the parties to choose the most precise weapon available, or consider alternative weapons and/or tactics.

The assessment of whether an attack is indiscriminate or disproportionate, and whether all feasible precautions have been taken, must not be based on hindsight but on the perspective of the commander based on the information available to him/her at the time of the attack. Such information includes the foreseeable effects of the weapons at his/her disposal in view of their inherent characteristics, as well as the circumstances of their use, including the physical environment in which the military objective is located and the vulnerability of the surrounding civilian population and civilian objects. Of these factors, the choice of weapon and the manner in which it will be used are those over which the commander has the greatest control. In this regard, the variables related to the choice and use of weapon that the commander can manipulate to respect the above-mentioned IHL rules include: the type and size of the warhead (munition), the type of fuse, the delivery system, and the distance from which the weapon is launched, as well as the angle and timing of the attack. The technical skills of the armed forces in the selection and use of weapons are also critical factors that will influence the outcome of an attack.Footnote ⁶⁴ Nonetheless, even after taking all such measures and precautions, certain explosive weapons may be prone to causing significant incidental effects on civilians and civilian objects when used in populated areas.

Although there is no dispute that any use of explosive weapons in populated areas must comply with the above IHL rules, there are divergent views on whether these rules sufficiently regulate the use of such weapons, or whether there is a need to clarify their interpretation or to develop new standards or rules. Based on the effects of explosive weapons in populated areas being witnessed today, there are serious questions regarding how the parties using such weapons are interpreting and applying IHL. Divergent practice of militaries, and contrasting views among experts and in the case law of international criminal tribunals regarding what is or is not legally acceptable, may point to ambiguities in IHL and the need for States to clarify their interpretation of the relevant IHL rules or to develop clearer standards to effectively protect civilians.

In any respect, the prohibition of indiscriminate attacks and the rules of proportionality and precautions in attack, each of which strikes a careful balance between considerations of military necessity and of humanity, were developed by States with the overarching objective of protecting civilians and civilian objects against the effects of hostilities. Any challenges that may arise in their interpretation and application to the use of explosive weapons in populated areas must be resolved with this overarching objective in mind. A number of these challenges are outlined below.

The use of explosive weapons in populated areas and the prohibition of indiscriminate attacks

The prohibition of indiscriminate attacks takes into account the fact that means and methods of warfare that can be used perfectly legitimately in some situations could, in other circumstances (including due to the manner in which they are used), be of a nature to strike military objectives and civilians and civilian objects without distinction.Footnote ⁶⁵ Warfare in populated areas is certainly a situation that may render indiscriminate explosive weapons that could be lawfully used in other circumstances, such as an open battlefield.

The prohibition of indiscriminate attacks includes those that employ a method or means of delivery that cannot be directed at a specific military objective.Footnote ⁶⁶ It is unclear what States consider to be the degree or standard of accuracy of a weapon that would be acceptable under this rule, generally or in a given operational situation. At any rate, any such standard of accuracy must be consistent with the general aim of protecting civilians from the effects of hostilities.

Still, the inherent inaccuracies of certain types of explosive weapon systems – such as many of the artillery, mortar and multiple rocket-launcher systems in use today, especially when using unguided munitions, as well as unguided air-delivered bombs – raise serious concerns under the prohibition of indiscriminate attacks when used in populated areas. While increasing the accuracy of delivery systems would help reduce the weapons' wide-area effects in populated areas, accuracy could be obviated by the use of large-calibre munitions – i.e. munitions that have a large destructive radius relative to the size of the military objective – which might still be in violation of IHL.

The interpretation of the prohibition of indiscriminate attacks may become more demanding with the development of new means and methods of warfare, notably with advances in precision weaponry. For example, the meaning of “clearly separate and distinct” military objectives in the prohibition of area bombardment is understood to mean a distance at least sufficiently large to permit the individual military objectives to be attacked separately.Footnote ⁶⁷ This understanding implies that the practical application of the prohibition of area bombardment, and by extension of the prohibition of indiscriminate attacks, could evolve based on the development of new weapons capabilities.

Reverberating effects of the use of explosive weapons in populated areas and the rules of proportionality and precautions in attack

The most visible effects of an attack using explosive weapons in populated areas are the immediate (or “direct”) civilian deaths and injuries and damage to civilian objects caused by the weapons' blast and fragmentation effects. Less visible, but equally devastating, are the reverberating effects (also referred to as the “indirect,” “knock-on” or “long-term” effects) of the attack, as consequences of incidental damage to certain civilian objects. For example, incidental damage to civilian homes is likely to cause the displacement of civilians, while incidental damage to hospitals is likely to cause the disruption of medical services, which in turn is likely to lead to the death of patients. Critical civilian infrastructure, such as vital water and electrical facilities and supply networks, is particularly fragile and vulnerable to the incidental effects of explosive weapons. The interconnectedness of the essential services that depend on critical infrastructure is such that disruption to one service will have knock-on effects on the other services. Thus, incidental damage to critical infrastructure can cause severe disruption to essential services on which the civilian population depends for its survival, such as health care, energy and water supplies and waste management, leading to the spread of disease and further deaths. These effects are multiplied in situations of protracted hostilities, where explosive weapons are used in populated areas over a prolonged period of time.

The question that arises is whether the reverberating effects of an attack using explosive weapons in populated areas must be taken into account by the attacker in assessing the expected incidental civilian casualties and damage to civilian objects as required under the IHL rules of proportionality and precautions in attack, recalled above. While acknowledging that it is both impractical and impossible for commanders to consider all possible effects of an attack, the ICRC considers that those reverberating effects that are foreseeable in the circumstances must be taken into account.

While there is support for this view, there remains uncertainty regarding which reverberating effects of an attack are “foreseeable.” Although, as explained above, this assessment is context-specific, the ICRC submits that it is framed in an objectivized way by what is foreseeable based on the standard of a “reasonably well-informed person in the circumstances [of the attacker], making reasonable use of the information available to him or her.”Footnote ⁶⁸ In this respect, it is submitted that those who plan and decide upon an attack have an obligation to do everything feasible to obtain information that will allow for a meaningful assessment of the foreseeable incidental effects on civilians and civilian objects. Moreover, what is objectively foreseeable by a commander in a given case must be informed by past experiences and lessons learned from his/her country's armed forces. It should also take into account the ever-growing experience of other armed forces in urban warfare, when available. In other words, as the understanding of the reverberating effects of the use of explosive weapons in populated areas increases, this knowledge informs future assessments and decisions under the rules of proportionality and precautions in attack.

It is unclear how armed forces integrate the obligation to take into account the foreseeable reverberating incidental effects on civilians and civilian objects into their military policies and practice, for example in collateral damage estimates. Based on the effects of explosive weapons in populated areas, namely the extensive civilian harm being witnessed today, there is significant doubt that reverberating effects are sufficiently factored in as required by the rules of proportionality and precautions in attack.

Towards a better understanding of States' positions, policies and practices

Warfare in densely populated areas, where military objectives are intermingled with protected persons and objects, represents an important operational challenge for armed forces. A military commander has the responsibility to minimize the incidental effects on civilians of an attack, and such a responsibility is heightened in an environment where civilians and civilian infrastructure are the main features of the theatre of operations. This holds equally true when the opposing party deliberately intermingles with civilians in order to shield its military activities – unlawful behaviour that nonetheless does not relieve the attacking party of its own obligations under IHL. Urban warfare thus entails a more demanding analytical process during the planning phase, as well as complex decision-making in real-time situations. As seen above, the military commander has a larger number of factors to take into account than when conducting hostilities in open areas.

Even more so than in open areas, an attacking party's ability to respect IHL in populated areas depends on the means and methods of warfare that it chooses to use, or not to use, taking into account their foreseeable effects in such environments, including their reverberating effects. Though some military practice, such as “collateral damage estimation” methodologies and “minimum safe distances,” as well as lessons learned from post-attack “battle damage assessments” and “after action reviews,” may help to minimize incidental harm to civilians, it remains unclear how these integrate the requirements of the rules of IHL discussed above.

What seems certain is that thorough training of armed forces in the selection and use of means and methods of warfare in populated areas, including on the technical capabilities of the weapons at their disposal, is critical to avoiding or minimizing incidental harm to civilians in this environment. Moreover, specific targeting directives applicable to the use of certain explosive weapons in populated areas may be required to ensure compliance with IHL.

Yet only a few armed forces are known to train specifically in urban warfare, or to otherwise apply specific limitations on the choice and use of explosive weapons in populated areas for the purpose of avoiding or minimizing incidental civilian harm. A better knowledge of existing military policy and practice, and more clarity on how States interpret and apply the relevant rules of IHL to the use of explosive weapons in populated areas, would help to inform debates about this important humanitarian issue, foster a possible convergence of views, and assist parties to armed conflicts who endeavour in good faith to comply with the law. Ultimately, this will lead to better protection of civilians in populated areas.

IHL rules regulating the conduct of hostilities and nuclear weapons

While IHL does not specifically prohibit nuclear weapons, their use is restricted by IHL's general rules regulating the conduct of hostilities, which apply to the use of all weapons in armed conflict.Footnote ⁸¹ Outlined below are the primary issues and concerns that arise when the use of nuclear weapons is considered under some of these key rules.

The prohibition of indiscriminate attacks: This rule prohibits attacks that are of a nature to strike military objectives and civilians or civilian objects without distinction. Such attacks include the use of weapons that cannot be directed at a specific military objective or that have effects that cannot be limited as required by IHL.

There are serious doubts as to whether nuclear weapons can be used in accordance with this rule. Nuclear weapons are designed to disperse heat, blast effects and radiation, and in most scenarios this will occur over very wide areas. For example, the use of a single 10 to 20 kiloton bomb (the yield of the bombs used in Hiroshima and Nagasaki, which are small bombs by today's standards) in or near a populated area will likely cause a very high number of civilian casualties, although the specific effects in a given case will depend on a variety of factors. The heat generated by the explosion can be expected to cause severe burns to exposed skin up to three kilometres from the epicentre, and massive destruction of buildings and infrastructure within several kilometres. Such effects would indicate an attack striking military objectives and civilians and civilian objects without distinction.

There is also a serious risk that the effects of such an explosion would not be limited in space and time, as required by IHL. This is particularly true for the intense fires, and possibly firestorms, that can result from the heat generated by a nuclear explosion. The same concern applies to radioactive fallout. While it is certain that radioactive particles will fall in the immediate area affected by the explosion, they can also disperse far from it, and even into other countries, carried by wind and other weather conditions.

Proportionality in attack: The nature of the effects produced by a nuclear weapon also raise doubts that an attack using such a weapon in or near a populated area could respect the rule of proportionality in attack. This requires that, for an attack against a military objective to proceed, the expected incidental civilian casualties and/or damage to civilian objects is not excessive in relation to the concrete and direct military advantage anticipated.

In the view of the ICRC, a party intending to use a nuclear weapon would be required to take into account, as part of the proportionality assessment, not only the immediate civilian deaths and injuries and damage to civilian objects (such as civilian homes, buildings and infrastructure) expected to result from the attack, but also the foreseeable reverberating effects of the attack.Footnote ⁸² These include those caused by damaged or destroyed water and electrical supply systems and other critical infrastructure supporting services essential for the civilian population, including health services. Foreseeable reverberating effects also include the long-term effects of exposure to radiation, in particular resulting illnesses and cancers in the civilian population. Such consequences can clearly be anticipated given what is now known about nuclear weapons.

Protection of the natural environment: Under this customary IHL rule, which slightly differs from that of Additional Protocol I, all means and methods of warfare must be employed with due regard to the protection and preservation of the natural environment and all feasible precautions must be taken to avoid, and in any event minimize, incidental damage to the environment. Thus, any decision to use nuclear weapons must take into account the potential impact on, and damage to, the environment, including foreseeable long-term effects. The use of even a single nuclear weapon may have significant effects on the natural environment due to the impact of dust, soot and radioactive particles on the atmosphere, soil, plants and animals.

Unnecessary suffering to combatants: Although combatants may be lawfully attacked in an armed conflict, IHL prohibits the use of weapons of a nature to cause them superfluous injury or unnecessary suffering, meaning injury or suffering that is out of proportion to the military advantage sought. The detonation of a nuclear weapon generates significant, and often fatal, levels of radiation with devastating immediate and long-term consequences to the health of exposed individuals. Effects include damage to the central nervous system and to the gastrointestinal tract and an increased risk of developing certain cancers, such as leukaemia and thyroid cancer. The short- and long-term illnesses, permanent disability and suffering caused by radiation exposure raise serious questions about the compatibility of nuclear weapons with this rule.

Difficulty envisaging compatibility of use of nuclear weapons with IHL

It has been argued by some States and commentators that low-yield nuclear weapons could be compatible with the rules of IHL.Footnote ⁸³ While the use of low-yield nuclear weapons in a remote area, such as against troops in a desert or against a fleet at sea, may not have immediate effects on civilians, there would remain significant concerns about the impact of radiation on combatants, the radiological contamination of the environment, and the eventual spread of radiation to civilian areas. Equally unsettling is the serious risk of nuclear weapons being used in response to such an attack, likely resulting in further escalation involving even greater use of nuclear weapons by both parties, with catastrophic humanitarian consequences.

In its 1996 Advisory Opinion, the ICJ concluded that the use of nuclear weapons “would generally be contrary to” the principles and rules of IHL. However, the ICJ was unable to decide whether such use would be lawful or unlawful, “in an extreme circumstance of self-defence, in which the very survival of a State would be at stake.” In this respect, the ICJ did not conclude that the use of nuclear weapons would be allowed in an extreme case of self-defence. Rather, it indicated that the state of international law and the facts at its disposal at the time did not allow it to reach a definitive conclusion.

The ICRC considers that the exercise of the right of self-defence – even in an extreme situation where the very survival of a State is at stake – can on no account release that State from its obligations under IHL. Self-defence must be exercised with due regard for IHL, whatever the circumstances, and not in violation of the very rules intended to mitigate the suffering caused by armed conflict.

The above concerns under IHL led the Movement to conclude in 2011 that “it is difficult to envisage how any use of nuclear weapons could be compatible with the requirements of international humanitarian law.” In the view of the ICRC, the new evidence and information that has emerged in recent years, including in international conferences on the humanitarian impact of nuclear weapons, cast further doubt on whether nuclear weapons could ever be used in accordance with the above-mentioned rules of IHL.

Preventing the use of nuclear weapons requires States to fulfil their existing obligations and commitments to pursue negotiations aimed at prohibiting their use and completely eliminating them through a legally binding international agreement. The ICRC has appealed to States to establish a time-bound framework to do so. It has also called on States that possess nuclear weapons to, in the meantime, diminish the risks of intentional or accidental nuclear detonations by reducing the role of nuclear weapons in their military doctrine and reducing the number of nuclear weapons on high alert, in accordance with existing commitments.

Regulating PMSCs: Complementary international initiatives

The Montreux Document constitutes an important building block of broader efforts to clarify, reaffirm and/or develop international legal standards aimed at achieving greater respect for international norms in situations where PMSCs operate. Several other international initiatives have also been launched in the past several years to regulate the activities of private contractors. For instance, discussions are taking place within the UN context on the possibility of elaborating an international convention to regulate PMSCs. Such an instrument would lay down new obligations binding on States, and could thus go beyond the Montreux Document, which primarily restated the already existing international obligations of States related to PMSCs. In this context, it should be recalled that the Montreux Document is not – and was not meant to be – the definitive and sole text capable of addressing legal issues relating to PMSCs.

Although other initiatives are distinct from, and take a different approach to, that of the Montreux Document, the ICRC is of the view that they should be considered as being complementary. The common goal of each is to promote respect for international law. Such initiatives also have an important role to play in ensuring that PMSCs do not commit acts that would be contrary to international law. What is ultimately important is that the different initiatives make up a mutually reinforcing network of obligations, standards and good practices that should serve to improve the protection of persons affected by armed conflict (or of those who find themselves in situations that fall below that threshold).

Montreux +5 Conference: Progress and challenges

Recognizing the potential humanitarian consequences arising from the activities of PMSCs, the ICRC's exclusively humanitarian goal is to promote respect for IHL and IHRL in situations of armed conflict in which such companies are present. It is with this aim that the ICRC continues to work for the full and effective implementation of the existing obligations of States under international law, as reflected in the Montreux Document.

In December 2013, Switzerland and the ICRC hosted the Montreux +5 Conference to mark the fifth anniversary of the finalization of the Document and to take stock of progress achieved. From an initial 17 States, the number of signatories has grown to 52, with the text also having been accepted by three international organizations. In addition to the increase in the number of endorsements, the humanitarian objectives underlying the Montreux Document may be said to have been significantly advanced since its adoption seven years ago. The Document has been instrumental in making it clear that international obligations apply to the activities of PMSCs. It has also helped raise awareness of States' obligations with respect to the operation of PMSCs, and of the importance of adopting and implementing adequate domestic legislation. Despite these results, much remains to be done going forward in order to adequately regulate the activities of PMSCs in national law and practice with a view to ensuring better respect for international law.

While several States have enacted domestic legislation on PMSCs, more States need to do so, and the relevant national laws and corresponding regulatory frameworks need to be clearer and more robust. States need to take action to clearly delimit the services that may or may not be contracted out to PMSCs. In this respect, whether a particular service could cause PMSC personnel to directly participate in hostilities should be given particular attention.Footnote ⁸⁵ Another area requiring further work is ensuring the accountability of and oversight over PMSCs and their personnel as regards violations of international and national law. A major challenge in this regard is the multinational nature of a large part of the industry. Given that several States can have a bearing on, or be impacted by, the operations of PMSCs, cooperation among States is essential. Put differently, States must take the necessary legislative and administrative measures in a concerted manner if respect for international law and accountability for violations involving PMSCs are to be ensured.

Another area of concern is the reliance of some States on PMSCs to train members of their security and military forces in IHL and IHRL. Given that adequate training is a key element in preventing violations of IHL, the provision of training services by PMSCs requires appropriate regulation and regular oversight by the States concerned. It must constantly be recalled that States remain accountable for supervising and enforcing respect for international law by PMSC personnel.

Montreux Document Forum: Taking the Montreux Document forward

The need to take the Montreux Document forward was at the centre of discussions at the Montreux +5 Conference, with participants strongly supporting the idea of institutionalizing a regular dialogue on the challenges faced in the implementation and promotion of the Document. To follow up on this proposal, Switzerland and the ICRC convened a series of preparatory meetings among Montreux Document participants during the course of 2014 to discuss the tasks and structure of the Montreux Document Forum (MDF). This led to the formal establishment of the Forum during a Constitutional Meeting held on 16 December 2014 in Geneva, which brought together over 50 States and three international organizations.

The objective of the MDF is to provide an informal platform for signatories to discuss and exchange information on challenges faced in the regulation of PMSCs. The Forum will aim to support national implementation of the rules and good practices contained in the Montreux Document and the development of practical implementation tools. It will further seek to facilitate the exchange of experiences on lessons learned, good practices and challenges related to the implementation of the text. It will likewise work to expand support for the Document among other States and international organizations; although the number of signatories has tripled in the last seven years, there is still a need to increase participation from States in all regions of the world and among international organizations.

The ICRC supports the establishment of the MDF and is committed to contributing to its future activities, in cooperation with Switzerland. It is anticipated that, by working on the implementation and promotion of the Document, the MDF will play an important role in ensuring greater respect for international law and thus enable greater protection for persons affected by PMSC operations. The ICRC encourages States and international organizations that have not yet done so to consider endorsing the Montreux Document. It also encourages Montreux Document participants to actively engage with and support the work of the MDF in order to ensure the necessary regulation of PMSCs.