Introduction
In recent decades, armed conflict has increasingly taken place in urban environments and near civilian concentrations. Recent conflicts have seen destructive fighting taking place in close proximity to densely populated cities.Footnote 1 In such settings, the boundary between military objectives and civilian spaces becomes increasingly difficult to maintain,Footnote 2 and this has significant negative ramifications for civilian protections. Urban infrastructure operates as an interconnected system rather than as isolated components, and disruption to one element, such as electricity or water, can cascade across multiple services, amplifying the impact on civilian life. The presence of military objectives or defensive activity in such areas places the civilian population and their infrastructure at risk. While the attacker is required under Article 57(2) of Additional Protocol I (API) to avoid and in any event minimize risk to civilians,Footnote 3 this provision does not prevent them from targeting legitimate military objectives that happen to be co-located with civilian persons/objects, or objectives that serve a dual-use function,Footnote 4 as long as proportionality is respected (Article 57(2)(a)(iii) of AP I).
The attacker’s perspective, however, is not the only one to consider. IHL has long considered the role of the defending party as equally crucial to reducing risks to the civilian population arising from military operations.Footnote 5 The most important obligation related to defenders is the “passive precautions” rule.Footnote 6 Found in Article 58 of AP I and considered reflective of customary law,Footnote 7 this rule requires States to avoid placing their military objectives near civilian persons/objects (subparagraph (b)), to remove civilians from military objectives (subparagraph (a)) and to otherwise take any other measures to protect the civilian population from dangers resulting from warfighting (subparagraph (c)). In this paper, we focus on the core rationale of subparagraphs (a) and (b), namely the desire to preclude – as far as possible – the intermingling of military assets with the civilian population.Footnote 8 Particularly in urban settings, such intermingling (both in terms of spatial proximity and functional interdependence) is often an unavoidable outcome of co-location, which we define as the close spatial proximity between military objectives and civilian life.
Despite Article 58 setting a clear obligation to segregate military objectives from the civilian population,Footnote 9 the implementation of this rule in many urban areas is inconsistent. Compared to the extensive corpus of “active” precautionary rules addressed to the attacking party, which are often scrutinized extensively after attacks involving civilian casualties,Footnote 10 Article 58’s passive precautionary obligations have received substantially less scholarly attention in general,Footnote 11 and States have enjoyed greater tolerance for their (lack of) implementation of this rule.Footnote 12 It is not uncommon to see ministries of defence located in the heart of urban centres or military bases located next to (and utilizing the infrastructure of) dense civilian settlements.
Despite factually being contrary to the requirements of Article 58, legal admonishment against such practices is rare. This is in prominent part due to the greater margin of appreciation provided by the feasibility clause embedded in the provision, which requires States to implement passive precautions (only) “to the maximum extent feasible”. States have operationalized the feasibility clause to encompass many factors and circumstances, which often has the effect of exempting them from maximally applying the provision. With regard to co-location, many conditions that are typical of urbanized areas – such as density, dual-use infrastructure and demographic shifts – are frequently invoked to argue that it would be “difficult or even impossible”Footnote 13 to execute segregation measures required under Article 58(a)–(b) (for a full analysis, see the following section below).
From a purely objective current-day assessment, it is hard to contradict these claims. Many densely populated States may have limited alternative space to relocate military objectives,Footnote 14 and others may not have the resource capacity to do so.Footnote 15 While such constraints are legitimate, they nevertheless have consequences: if conflict does break out in such areas, the proximate civilian population will face greater dangers – a societally undesirable outcome that IHL seeks to avoid.
In this paper, we advance a different perspective on the issue of passive precautions and feasibility. While many modern urbanized areas may factually not (or no longer) permit States to implement segregation measures, these current-day realities should not be viewed as disjunctive in time. Instead, we argue that they are shaped by measures, policies or omissions taken by the State in the past that are not necessarily related to defence, such as politics, planning, zoning and housing, economic policies, infrastructure development and education.Footnote 16 We term these “root causes of co-location”. It is these root causes which create the structural conditions typical of many urban areas, such as interconnectedness and intermingling, which subsequently render it “infeasible” for States to implement passive precautions in time of armed conflict. Ultimately, we argue that the current “infeasibility” of applying Article 58(a)–(b) as experienced by many States may be an avoidable outcome, and indeed one that should be avoided wherever possible to improve the protection of the civilian population. To achieve this, however, a more grounded understanding is necessary as to what these root causes are, what structural obstacles they create, and how to mitigate or address them.
We aim to achieve the following. After the present introduction, in the first substantive section, we engage in a doctrinal analysis of the feasibility qualifier as it applies to passive precautions, and identify a set of conditions that are commonly raised as justifications for why States consider it infeasible to maximally implement Article 58(a)–(b). In the second section, we then establish the central thesis of the paper, which challenges the notion that such conditions are inevitable – instead, we argue that many are the predictable results of (avoidable) policies taken during peacetime. We substantiate this assertion in the third section by establishing a four-driver framework of structural causes of co-location which captures how choices in spatial development, infrastructure design, institutional arrangements, and economic and policy priorities ultimately shape what is “feasible” for States. In this section, we present examples from existing governance frameworks which demonstrate how these drivers manifest in practice. Based on these findings, we argue in the fourth section that “feasibility” should be reconceptualized as a legal-spatial concept, one that should be read as a (potentially avoidable) outcome of many prior policy choices. The fifth section provides recommendations for improving civilian protection based on our diagnosis of structural causes of co-location, and is followed by an overall conclusion and suggested steps forward in the sixth section.
As a final point, this paper does not aim to redefine the feasibility qualifier, nor claim that States currently invoking (in)feasibility in good faith are in violation of Article 58. As the following section discusses, the feasibility qualifier has an important function in IHL – namely, to ensure that legal obligations remain aligned with operational realities. This paper does not extend the passive precautions rule to the point of unworkability; instead, we offer a new perspective on the rule’s feasibility qualifier by arguing that States may have options to enhance civilian protection by looking beyond the operational moment. This paper, above all, is a constructive framework that aims to help States determine the structural causes of their inability to segregate, and identify solutions to overcome these obstacles.
Passive precautions and their feasibility clause
In this section, we lay the groundwork for our further analysis by first considering in detail the rationale behind the segregation rule in Article 58, the intent behind its feasibility qualifier, and what conditions have traditionally been considered as rendering the taking of passive precautions “infeasible”.
The two segregation rules
The duty to avoid co-locating military objectives and civilian populations/objects has a long history, even being found in the Lieber Code,Footnote 17 and is reflective of customary law.Footnote 18 Its underlying rationale is straightforward: placing military objectives near civilians and populated areas significantly weakens the effective protection afforded to the civilian population.Footnote 19 Frequently, “segregating civilians and civilian objects from military objectives is the best source of protection possible”.Footnote 20 Indeed, while Article 58(c) requires States to take any other possible measures to protect the civilian population from dangers (even if segregation is successfulFootnote 21), this clause is often characterized as a crucial stop-gap if segregation cannot be performed satisfactorily,Footnote 22 further underlining the importance of avoiding co-location in the first place.
Despite being formulated in AP I as being addressed to “Parties to the conflict”, Article 58 is often considered as belonging to IHL’s few antebellum obligations,Footnote 23 which should be implemented as early as possible and even before hostilities have commenced.Footnote 24 As Jensen notes, States cannot wait until attacks arrive to start preparing the battlespace for civilian protection, as many passive precautions (such as building air-raid shelters) require “actions taken in advance, not just in response”.Footnote 25 Other passive precautions (like broadcasting air-raid warnings), however, are decidedly more reactive. For the analysis that follows, it is useful to briefly consider Article 58(a)–(b) in greater detail and to distinguish between passive precautions that are structural-preventive (requiring longer-term planning and preparations) and those that are tactical and reactive.
Article 58(a)–(b) describes two mechanisms through which co-location can be avoided. Subparagraph (b) requires States to avoid placing military objectives near civilian concentrations.Footnote 26 It has a more tactical prong that limits transient forms of co-location – for example, military units taking positions or routes near civilian populations/objects should restrict such movement or stay to the minimum duration possibleFootnote 27 – but is primarily structural-preventive in nature.Footnote 28 For instance, it requires militaries to plan where they build or place bases, supply depots, installations or other military objectives, and to consider whether this positioning could pose dangers to civilians in the vicinity.Footnote 29 Despite this emphasis on long-term planning, subparagraph (b) is theoretically straightforward to implement, as it focuses on military positioning – an element that the State (through its ministry of defence and armed forces) has more direct control over.
Subparagraph (a), meanwhile, requires States to remove the civilian population/objects from the vicinity of military objectives, making it an inverse obligation of subparagraph (b). Both in literature and in practice, this obligation is generally associated with wartime evacuations, particularly of vulnerable parts of the civilian population.Footnote 30 Subparagraph (a) nevertheless also has a less frequently mentioned preparatory prong, in the form of drawing up the aforementioned evacuation plans/routes during peacetime and earmarking resources to effectively execute them when war breaks out.Footnote 31 Having the civilian population as its primary addressees, however, this subparagraph presents more challenges in its application than subparagraph (b). Civilians may resist relocation, and relocation itself may expose them to greater danger, hardship or trauma; such risks must be taken into account when implementing the obligation under Article 58(a) of AP I.Footnote 32 Additionally, the measure’s execution could depend on prior coordination with civil authorities,Footnote 33 and furthermore, it is not always possible to foresee what may become a target in the future, as military objectives by use and purpose (as opposed to nature and location)Footnote 34 shift statuses more rapidly depending on prevailing circumstances.Footnote 35 This limits the extent of pre-planning that can be doneFootnote 36 and explains why subparagraph (a) emphasizes a more tactical, reactive approach.
It is worth noting that the passive precautions rule also includes subparagraph (c), which pertains to any “other necessary precautions” that the State could undertake to protect civilians against the dangers of warfare. This subparagraph is an open-ended obligation, common examples of which include issuing warnings to civilians, designing shelters and strengthening civil defence.Footnote 37 This article focuses on subparagraphs (a) and (b) for their more direct focus on segregation – the main subject of the current analysis – but it is important to remember that even where these subparagraphs are fully satisfied, States are still required to take any further mitigations possible pursuant to subparagraph (c).
What is “infeasible”?
The prior analysis highlighted a few challenges that may be encountered in applying Article 58(a)–(b). It is undeniable that many measures that could be ideal for maximizing the protection of the civilian population “may be very difficult, if not impossible, to realize” in practice.Footnote 38 Cognizant of this fact, the precautionary measures that States are required to undertake are limited by the phrase “to the maximum extent feasible”. The underlying rationale behind the feasibility clause is that States cannot be expected to take precautions that are impossible, overly onerous, or impractical.Footnote 39
The feasibility clause is necessary to ensure the workability of IHL, but simultaneously provides States with a broad margin of appreciation that can serve as an easy justification for non-implementation.Footnote 40 Furthermore, the circumstances that legitimately trigger it have received limited scholarly attention. This subsection addresses that gap.
First, a precautionary measure can be considered “infeasible” if it is militarily prejudicial. During the Diplomatic Conference leading up to the Additional Protocols, States emphasized that passive precautionary obligations could not adversely affect their ability to organize their national defence in the most effective way.Footnote 41 In State practice, “military considerations” are frequently invoked as an (overriding) factor when determining feasibility.Footnote 42 For example, it would be understandably infeasible to require States to move military objectives or installations far away from civilian concentrations if this would render these assets unduly conspicuous or vulnerable to the enemy.Footnote 43 This seems to be an inherent dilemma at the core of the segregation rule, where performing the segregation may make military objectives more readily identifiable by the enemy than they would be if they were to remain co-located.Footnote 44 At the same time, it would be contrary to the spirit of the passive precautionary rule to excuse any co-location on the pretext that moving military assets away from civilian positions is inherently more dangerous (and thus would be “infeasible”). Presumably, the viability of invoking this justification would depend on whether a relatively concrete heightened danger can be identified from executing a segregation measure, instead of the general notion that segregation introduces risk.
Second, a measure can be considered “infeasible” for practical or logistical reasons. These may include very obvious limitations, such as the fact that “[n]othing can be done to move immovable civilian objects in order to protect them from attack”.Footnote 45 With the technological developments that have taken place in recent decades, the pervasive reliance of militaries on civilian software, systems, satellites and lines of communication may also make it factually impossible to fully decouple.Footnote 46 States have further cited the potential economic cost of implementing certain precautionary measures – such as large-scale relocations – as a reason for being unable to implement them.Footnote 47 Finally, geography is a factor: Switzerland, for example, has argued that its heavily mountainous terrain leaves little room to segregate objects of vital economic and military importance, which are all concentrated in valleys where civilian centres are also located.Footnote 48
Beyond the two general rationales above, the following rationales have also been raised:
• The State is not required to undertake a precaution if it would not materially improve the civilians’ protection. For example, evacuating civilians may serve little purpose if there is no safer location to move them to,Footnote 49 or if the enemy is deliberately targeting civilians.Footnote 50
• Under certain interpretations, a “grandfather clause”Footnote 51 has been read into the segregation rule which exempts military installations or objects that pre-date modern IHL rules from needing to be relocated.Footnote 52 For example, the Commentary on the HPCR Manual on International Law Applicable to Air and Missile Warfare argues that many “Ministries of Defence and other military objectives have long been located in urban areas and cannot be removed”.Footnote 53
The feasibility clause in urban settings
Applying the above findings to urban environments, which are characterized by a high degree of civilian density, interconnectivity, and dual-use objects,Footnote 54 we find that many of the aforementioned rationales have been used to justify why co-location occurs so frequently in urban settings, despite Article 58 mandating otherwise.
In some cases, it is argued that “avoiding locating military objectives in populated areas may simply not be feasible”.Footnote 55 Many States with high population densities argue that they might need to place (some) military assets in populated areas in order to mount an effective defence.Footnote 56 As long as States do not deliberately abuse civilian objects for military purposes (e.g., storing ammunition in, or firing from, civilian buildings), the fact that hostilities take place in the vicinity of the civilian population/objects would thus be viewed as an “unavoidable consequence of the particular context”, instead of as a failure to segregate.Footnote 57
Some military objectives are invariably dual-use, or need to be positioned close to civilian concentrations. Railway stations, airports, seaports, factories, power plants and digital infrastructure often serve both military and civilian purposes, and as the International Committee of the Red Cross (ICRC) Customary IHL Study points out, they “may even be located near or inside densely populated areas on purpose”.Footnote 58 While it may be theoretically possible to completely segment such objects/infrastructure by designing two parallel systems, the time and resources required to do so would be unreasonable, and it would thus be infeasible.Footnote 59 Military objectives may also be positioned near civilian concentrations “on purpose” because this is necessary or practical for the everyday functioning of the State; as Schmitt notes, some military objectives “need to be located in or near particular locations, such as a key line of communication or the seat of government”.Footnote 60 This includes ministries of defence, which are usually placed in the heart of capital cities.
Military bases, along with their personnel, may be positioned near urban areas for practical reasons. Hays Parks remarks:
For hygiene, morale, communications, and other reasons, military personnel and units historically have been billeted or housed in populated areas, and the doctrine of most nations provides for a continuation of this practice; it should not necessarily be viewed as sinister.Footnote 61
Sometimes, civilians come to military objectives instead of the other way around. “Demographic shifts” are commonly cited in State practice to explain why military objectives sometimes become located in or near cities when this originally was not the case.Footnote 62 Iran, for example, has reported how “due to [the] expansion of city limits [over] the years, some garrisons are now located in the center of the cities”.Footnote 63 States in which civilians have “come to” the military objective rarely undertake proactive relocation, implying that demographic change is treated as a circumstance that justifies inaction.Footnote 64 Finally, as mentioned above, the “grandfather clause” may be relevant for many military objectives in urban areas whose existence pre-dates the modern passive precautionary rule.
Central theses
From the above analysis of how feasibility has been operationalized, it is clear that feasibility is often invoked with respect to a moment in time, by reference to current-day realities in the field. As we have argued, however, the passive precautionary rule includes a strong antebellum component, in that it relies on (and expects) longer-term planning and foresight by States in order to optimally implement its protections. The persistent difficulty of separating military objectives from civilian environments cannot be explained solely by what happens during hostilities – it must be understood in relation to the conditions that make such separation difficult before hostilities even begin. The issue, therefore, is not only how feasibility is applied, but how it is conceptualized. As currently framed, feasibility captures constraints without taking into account how those constraints are produced.
In this paper, we propose an alternate means of thinking about passive precautions, centred around the premise that peacetime drivers exist which narrow what is ultimately “feasible” to implement under Article 58 when conflict arises. Our central thesis is as follows:
What is commonly described as “infeasible” under Article 58(a)–(b) is, in many cases, not a natural or unavoidable condition, but one shaped by governance and policy choices that pre-date conflict, which operate through identifiable mechanisms and which are, at least in part, amenable to reform.
Critically, this production of infeasibility is caused not by a single decision or actor, but through the cumulative effect of governance choices made across multiple sectors and time horizons, none of which individually relate to civilian protection, but which all collectively determine its limits. A corollary thesis follows:
Feasibility under Article 58 is not binary. It ranges across a spectrum from conditions that are genuinely unavoidable – such as certain geographic realities or forms of critical infrastructure interdependence that cannot practically be resolved – to conditions that are institutionally produced through regulatory design, planning priorities and coordination failures, and are therefore open to intervention.
The analytical task is therefore not only to determine whether a given situation is “feasible” or “infeasible”, but to identify which type of infeasibility is at stake – namely, one that truly cannot be altered, or one that reflects prior governance choices which could have been (and could still be) made differently. Where the infeasibility is of the latter kind, the passive precautions obligation retains its normative purchase even before conflict begins, by directing attention toward the peacetime governance arrangements that have produced such infeasibility.
The subsequent sections develop a three-step diagnostic model: (1) identifying which structural drivers are operative in a given context; (2) tracing their root causes to distinguish genuinely unavoidable constraints from preventable governance failures; and (3) linking that diagnosis to targeted policy interventions. By doing this, we substantiate our two theses advanced in this section and demonstrate how thinking in broader temporal terms provides a new perspective on how States can take actions to ultimately expand their ability to implement precautionary measures when war arrives.
Structural causes of co-location
This section develops a four-driver framework which identifies structural factors that generate co-location. Those four drivers are derived from an interdisciplinary review of IHL doctrine, urban warfare studies, spatial planning research and infrastructure governance literature, integrated here to address the legal question of what renders passive precautions infeasible. These factors do not arise in isolation but are repeatedly reproduced across contexts, and their cumulative effect is to embed civilian vulnerability as a structural rather than a situational condition. Understanding co-location, therefore, requires moving beyond the moment of attack and towards examining the structural conditions that generate military–civilian proximity. We focus on four interrelated drivers – spatial constraints, infrastructural interdependence, institutional fragmentation and political-economic priorities – and trace the mechanisms through which they produce military–civilian proximity.
Below, we provide both a theoretical foundation for each of our four drivers, and practical examples to demonstrate how these factors manifest in concrete governance and policy contexts. These examples are illustrative and are drawn from many different countries, but we have chosen to provide many examples from the Indonesian context, for a few reasons. First and most practically, as Indonesian scholars, we are most knowledgeable on Indonesian governance structures and practices. Second, we see Indonesia as a solid archetype for many rapidly developing States that experience challenges related to Article 58 implementation. As the world’s fourth-most populous country, Indonesia is undergoing rapid and sustained urbanization, with its urban population share nearly doubling from 30% in 1990 to almost 59% in 2024,Footnote 65 creating acute structural pressure between civilian density and military positioning. More distinctively, the Indonesian legal framework explicitly institutionalizes the integration of defence functions into civilian spatial planning through dedicated instruments, thereby formally codifying the governance mechanisms that produce co-location. This is analytically helpful, allowing regulatory tracing across multiple layers of planning and defence instruments. Finally, Indonesia’s inclusion helps diversify the empirical base of IHL scholarship, beyond its traditional Western focus.Footnote 66
Spatial constraints
Article 58 presumes that military objectives and civilian populations can, as a matter of practice, be kept meaningfully apart. Increasingly, however, this assumption no longer reflects the spatial realities of contemporary societies. Across much of the world, decades of urban expansion, demographic growth, and the concentration of critical infrastructure have progressively narrowed the physical distance between civilian settlements and military installations. What was once conceived as a practicable geographical distinction has become substantially more difficult to maintain.
This transformation is not confined to a single jurisdiction. In Israel, several major military installations have remained embedded in growing cities; in Beersheba, for instance, the Southern Command base sits in the heart of the Old City, surrounded by residential, commercial and government buildings, and for decades its presence shaped the direction in which the city expanded.Footnote 67 The experience of Ukraine reveals a different but equally significant dimension, with railways, major road networks, ports, airfields and other strategically important infrastructure closely embedded within urban environments, illustrating how the growth of cities can bring civilian space and militarily significant infrastructure into increasingly close proximity with each other.Footnote 68 These developments suggest that spatial constraints arise not only from operational choices made during armed conflict, but also from long-term patterns of urbanization that fundamentally reshape the geography of military and civilian space.
Indonesia presents an especially complex manifestation of these broader dynamics; unlike in many continental States, the challenge there extends beyond urban expansion alone. As the world’s largest archipelagic State, Indonesia combines a fragmented geography and dispersed island settlements with a population and economy concentrated on a few core islands, leaving most islands economically dependent on inter-island shipping and a limited number of ports.Footnote 69 These conditions can reduce the practical possibilities for maintaining meaningful physical separation between military objectives and civilian populations, particularly where the same ports and airfields must serve both civilian traffic and defence functions. Indonesian defence planning guidance, for instance, designates Juanda Airport in Surabaya as serving both naval and civilian aircraft (see the following subsection below).Footnote 70
As discussed in the above subsection on “The Feasibility Clause in Urban Settings”, evolving demographics or space limitations are frequently mentioned as a cause of co-location. These examples are often cited as evidence of constraint, but are better understood as evidence of process. It is natural and foreseeable for urban spaces to evolve;Footnote 71 military installations that were once peripheral become surrounded by civilian development, residential areas expand along transport corridors that also serve strategic purposes, and industrial and logistical zones evolve into mixed-use environments. Co-location in such contexts is not inevitable – instead, frequently, the separation that previously existed is simply not maintained. Urban warfare analysis consistently shows that density, verticality and constrained space reduce the ability to maintain clear distinctions.Footnote 72 Urbanization and warfare are mutually constitutive, meaning that cities are not neutral backdrops but historically shaped environments that condition military action.Footnote 73
The root cause of this driver, therefore, lies not in geography or demographics per se, but in how space is governed. If urban expansion proceeds without mechanisms to preserve separation, if zoning/land-use regulations do not incorporate civilian protection considerations, and if no mandatory reassessments of military placements are triggered as urban growth occurs, spatial constraints become the accumulated result of how space has (not) been governed.
To demonstrate how this root cause manifests in practice, we will draw from an Indonesian case study. In the Indonesian context, the analysis of spatial constraints must begin with their primary normative foundation: Law No. 26 of 2007 on Spatial Planning.Footnote 74 This law positions space as a system encompassing the planning, utilization and control of space to achieve safety, comfort, productivity and sustainability. Within this framework, space is not a neutral entity but the outcome of policy interventions that regulate the distribution of human activities, infrastructure, and strategic interests within a unified system.Footnote 75
What is equally significant is what Law No. 26 does not regulate explicitly. The spatial planning system does not directly incorporate the risk to the civilian population due to proximity to military objectives as variables in spatial design. It operates according to a logic of development, efficiency and sustainability. Within this logic, co-location appears not appear as a system failure but as a consequence of different priorities.
Indonesian spatial planning literature reinforces this reading. Urban planning studies show that spatial planning serves as a mechanism for integrating various sectoral interests (economic, social, environmental, infrastructural) that frequently produce mixed, not fully separated, spatial configurations.Footnote 76 The tendency toward functional integration is therefore part of how the system is designed.
This integration becomes more explicit when defence functions are incorporated into the spatial planning framework through subsidiary regulations. Government Regulation No. 68 of 2014 on Defence Area Planning states that national territory may be used for defence purposes in both peacetime and wartime, and that defence area planning must be integrated with national and regional spatial planning.Footnote 77 At this point, the relationship between the civilian and defence space is no longer external, but institutionalized within a single planning system.
Instruments such as the Defence Area Plan and the Detailed Defence Area Plan (Rencana Rinci Wilayah Pertahanan, RRWP) then operationalize this integration by incorporating defence functions as inputs for the preparation of regional spatial plans (rencana tata ruang wilayah, RTRWs) and detailed spatial plans (rencana detail tata ruang, RDTRs).Footnote 78 Technical guidelines are explicitly designed to ensure that defence interests are incorporated into every level of spatial planning, from the national RTRW down to the RDTR and strategic area zoning.
The consequence is clear. Co-location in the Indonesian context emerges not as an anomaly but as the result of a regulatory design that explicitly integrates defence functions into the development space. Under such conditions, civil–military separation does not always take priority. This is most evident in the concept of overlapping defence areas (kawasan pertahanan tumpang tindih), in which defence functions can be superimposed on other spatial functions, whether permanently or temporarily.Footnote 79 Normatively this is a control mechanism, but ultimately it indicates a mindset whereby civil–military proximity is merely managed rather than deliberately prevented.
The same pattern is visible in zoning arrangements. Regulation does not always prohibit civilian activities around defence objects; rather, it regulates them under the categories of “permitted”, “conditionally permitted” and “not permitted”.Footnote 80 This shows that the system operates through a logic of compatibility rather than absolute segregation. Such an approach enables control, but also risks normalizing co-location as an ordinary feature of the built environment.
As noted above, the root cause of this driver thus lies not in geography but in regulatory design. The foundational spatial principle in Indonesian law is integration, not separation. Risk to civilians from military proximity is absent as a planning variable. No mechanism requires mandatory reassessment of military placements as urban growth occurs, and no criterion within the spatial plan’s review cycle explicitly addresses civilian protection in conflict scenarios. Spatial constraint in Indonesia is therefore produced through the way in which space is legally organized.
The regulatory framework itself provides strong indicative evidence of two regulatory gaps: the absence of explicit civilian protection considerations in spatial planning and the lack of review mechanisms addressing changes in military–civilian proximity. The Defence Sector Content Guidelines, which provide guidance for integrating defence considerations into spatial planning instruments, do not identify civilian protection in armed conflict or civilian risk arising from proximity to military objectives among the considerations expressly addressed in its spatial-use controls.Footnote 81 Civilian risk from military proximity does not appear as a criterion alongside the environmental, disaster and carrying-capacity risks that spatial plans must address. Similarly, no review mechanism within the RTRW or RDTR cycle is triggered by changes in civil–military proximity as urban growth occurs. The regulatory silence on these two points is analytically significant: it confirms that civilian protection considerations are structurally absent (instead of merely overlooked in practice) in the instruments that govern spatial planning preparation and review. The proximity between civilian and military functions in the Indonesian context is therefore better understood as an outcome of the spatial governance configuration than as a wholly unavoidable condition.
Infrastructure interdependence
Even where spatial separation exists, functional separation often does not. Modern urban systems are deeply interconnected; electricity, water, transport and communication infrastructure form networks in which disruptions spread across sectors. This empirical pattern is well documented.
The war in Russia/Ukraine provides a particularly revealing illustration of infrastructure interdependence, with effects spreading well beyond the facilities that are targeted in the conduct of hostilities. Public transport and food production have been crippled, hospitals can no longer perform surgery, sewage treatment plants have stopped operating, and some ten million people have been left without electricity, running water or heating. These shared infrastructure networks also serve military operations – transport systems that allow the armed forces to operate are also used to evacuate civilians, satellite internet connects military units and civilian services alike, and rail hubs, ports and airfields embedded in and around cities carry both civilian and military traffic.Footnote 82
Comparable patterns had already emerged during earlier conflicts. In Yemen, disruption of power and fuel supply has undermined water supply, sanitation and health services.Footnote 83 In Iraq, the destruction of electricity infrastructure generated prolonged failures in water treatment, sanitation and public health systems, illustrating that the humanitarian consequences of attacking interconnected infrastructure often unfold gradually rather than immediately.Footnote 84 This is a structural feature of cities: complex systems amplify indirect effects, making it impossible to treat damage as isolated. These are not incidental consequences but predictable outcomes of choosing system interdependence.
The root cause of this driver lies in how infrastructure is designed: systems are built for efficiency, not civilian protection. Centralized networks maximize performance under normal conditions but create vulnerabilities under stress. When one node fails, the effects spread due to the system’s design.Footnote 85 Limited infrastructure redundancy, the absence of cascading risk assessment requirements and the functional entanglement of military installations within civilian service networks are products of planning priorities that may have systematically excluded civilian protection in conflict conditions from the design criteria.
In Indonesia, defence planning guidance for spatial plans treats key transport infrastructure as part of the defence estate. It requires naval piers and ports and air base runways to be incorporated into spatial plans at every level as transport networks related to defence interests, designates the international airport serving the capital as a strategic national vital object equipped with air defence positions, provides for an airport serving both naval and civilian aircraft, and requires air bases to have access to arterial or toll roads usable as runways for fighter aircraft.Footnote 86 This demonstrates that dual-use infrastructure is not an exception but is rather part of the system’s design.
Indonesia’s long-standing practice of civil enclave airports illustrates this concretely. Articles 257–259 of the 2009 Law on Aviation provide the legal basis for the joint use of civilian airports and military air bases under specified circumstances,Footnote 87 while institutional arrangements between the Indonesian Air Force, the Directorate-General of Civil Aviation, and airport operators govern their implementation. As a result, airports such as Halim Perdanakusuma (Jakarta), Ahmad Yani (Semarang), Adi Soemarmo (Solo) and Juanda (Surabaya) simultaneously serve civilian transportation and defence purposes through shared operational infrastructure.Footnote 88
Such aviation infrastructure, in other words, cannot be understood as exclusively civilian or exclusively military. Instead, it functions simultaneously as a node for civilian mobility, national connectivity, and defence operations.Footnote 89 This dual-use character further complicates the practical application of Article 58, since the protection of civilians cannot be assessed solely by reference to spatial distance or direct military use. Instead, the functional entanglement between systems must be considered in a broader sense. Even if the facilities do not serve an immediate military purpose during peacetime, the impact of any military operations in such an environment when war arrives can propagate beyond the initial target through these shared networks.
This same logic extends to how Indonesian infrastructure is classified for planning purposes. Systems are built and regulated for efficiency and connectivity, without incorporating assessments of cascading civilian risk in conflict scenarios. RRWP classifications do not address infrastructure interdependence as a civilian protection parameter, and the Defence Area Planning Regulation permits defence functions across the national territory without conditioning that permission on an infrastructure risk assessment. The result is that civilian risk becomes inevitably embedded in the system by design.
Institutional fragmentation
The third driver operates at the level of governance: co-location is rarely the result of a single decision, but is often produced through a series of uncoordinated decisions.Footnote 90 Spatial planning authorities prioritize land-use efficiency, defence institutions prioritize strategic positioning, and infrastructure agencies prioritize connectivity and service delivery. These priorities are not inherently incompatible, but they are rarely coordinated in practice.
Urban governance research reinforces this point. Research on urban governance shows that spatial planning, infrastructure management, and security policy typically operate within separate institutional frameworks, and that coordination across them is neither automatic nor, in many systems, mandatory.Footnote 91 None of these frameworks, to our knowledge, requires civilian protection in armed conflict to be assessed across them. The result is a structural condition in which no single actor produces co-location, yet all contribute to it. Because the outcome is cumulative, responsibility is diffused, and co-location appears as a wartime constraint rather than a product of peacetime policies.
The root cause of this driver lies in distinct regulatory logics that operate without a coordination requirement for assessing civilian protection. Spatial planning, infrastructure governance, and defence policy typically function within separate institutional frameworks with distinct mandates, planning horizons and accountability structures. Overlapping mandates and institutional silos mean that risks emerge as by-products of routine administrative decisions. Because no single institution is responsible for anticipating the civilian protection implications of co-location, those implications are neither anticipated nor mitigated.
This dynamic is also present in Indonesia. Normatively, the Indonesian legal system requires integration of the defence sector within spatial planning, but in practice, defence planning, spatial planning and IHL implementation operate within different institutional frameworks. This is not uncommon: the widespread establishment of national IHL coordination mechanisms suggests that integrating humanitarian obligations into cross-sectoral governance is a common challenge across States.Footnote 92 Indeed, States are encouraged to establish national IHL committees precisely to provide support in cross-ministerial and cross-stakeholder coordination.Footnote 93 Indonesia reflects this pattern by establishing the National Committee on the Application and Study of IHL (Panitia Tetap Penerapan dan Penelitian Hukum Humaniter Internasional) (the National Committee), coordinated by the Directorate-General of General Legal Administration of the Ministry of Law, and involving various ministries and institutions, including the National Armed Forces.
At the same time, national IHL committees provide a potentially useful institutional entry point for bringing civilian protection considerations into dialogue with policy sectors that are not traditionally associated with IHL implementation, including spatial planning and infrastructure governance. The existence of Indonesia’s National Committee demonstrates coordination efforts but also confirms that such coordination is challenging, and not inherent in the system. If integration occurred naturally, an additional mechanism of this kind would not be necessary.
This structural pattern is confirmed by the National Committee’s own stated mandate. Since its establishment, the National Committee’s published activities have centred on treaty ratification studies, dissemination of IHL and capacity-building – functions oriented toward legal harmonization more generically rather than spatial or civilian protection coordination specifically.Footnote 94 Cross-sectoral coordination therefore does take place, but it focuses primarily on harmonizing institutional functions and authority related to IHL implementation in general, rather than on civilian protection specifically in the context of co-location. As a result, civil–military proximity is managed as an administrative and operational matter rather than as a civilian protection risk, which requires structural anticipation.
Co-location, in other words, can also emerge as a cumulative by-product of routine governance decisions across multiple sectors, a consequence of distinct regulatory logics operating without any coordination requirement for civilian protection assessment.
Political and economic priorities
If the previous three factors explain how co-location emerges, political and economic considerations explain why it persists. Urban space concentrates power, infrastructure and economic value in ways that make the co-location of military and civilian functions actively preferable.Footnote 95 Military facilities are deliberately positioned near centres of government, major transport hubs and communication networks because proximity serves both operational and political purposes. Dual-use infrastructure, such as major airports, seaports, rail hubs and energy systems, is located in densely populated areas because it is most efficient and politically and economically desirable to do so. Relocation entails financial costs, operational disruptions and political trade-offs that States are rarely willing to bear.Footnote 96 Civilian protection consequently becomes merely one consideration among many, and is usually subordinated to strategic and economic objectives in practice.
The root cause of this driver lies in incentive structures that systematically favour integration over separation.Footnote 97 Path dependencies created by decades of existing military infrastructure in urban centres make relocation increasingly costly over time, embedding civilian risk within the urban fabric as a systemic outcome of policy choice. Defence planning frameworks oriented toward operational efficiency, and the absence of civilian protection criteria in infrastructure investment decisions, reproduce this condition across successive planning cycles.
In Indonesia, defence infrastructure has historically been concentrated in major urban centres, including the headquarters of all three services, fuel depots and ammunition stores in the capital itself, and relocation is structurally difficult, since a defence area may be converted to other uses only once a replacement site meeting defence criteria has been prepared.Footnote 98 Minister of Defence Regulation 17 of 2021 illustrates how this incentive structure is reproduced institutionally.Footnote 99 The regulation defines risk in purely organizational terms – as an event with undesired consequences for institutional goals and objectives – and structures risk identification around four generic contexts: strategic, operational, reporting and compliance.Footnote 100 Nothing in this taxonomy provides a category for civilian or spatial risk of any kind, let alone one specific to civil–military co-location. Civilian risk arising from co-location is therefore not currently treated as a measurable and manageable category within existing defence risk management instruments, often making it invisible as a policy item.
Flexible zone classifications within the spatial planning system further reinforce this dynamic. Instead of confining the military footprint, they allow defence functions to be overlaid on land designated for other uses where those functions are temporary, and they require the land surrounding military bases to support base functions. Integration over separation is thus built in at two levels: in decisions on where individual defence facilities are located, and in the regulatory categories that govern those decisions.
This dynamic is not unique to Indonesia. Marine Corps Air Station Futenma sits in the heart of the densely built-up residential area of Ginowan City, Okinawa; the United States and Japan agreed as early as 1996 to relocate it to a proposed offshore facility elsewhere in Okinawa, yet the move has long stalled due to Okinawan resistance, expressed in successive elections and mass demonstrations, and environmental concerns about the replacement facility.Footnote 101 Yongsan Garrison, which has housed foreign troops in central Seoul since the late nineteenth century, illustrates the financial side of the same problem. South Korea and the United States agreed to its relocation in 1990, but negotiations stalled over cost allocation and Korea’s economic crisis, resuming only after a new presidential agreement in 2003. The site was not scheduled for return until 2018.Footnote 102 In both cases, the underlying recognition that continued co-location was undesirable long predated any actual relocation. The constraint was political and financial rather than technical or legal, mirroring the pattern observed in the Indonesian case above.
Synthesis
The analysis above shows that the four drivers do not operate independently. They are mutually reinforcing and cumulatively constrain the “feasibility space” under Article 58 across the planning system, infrastructure governance, military doctrine and legislative design.
The Indonesian evidence, which this analysis has drawn on most extensively, could in principle support alternative interpretations. Indonesia’s archipelagic geography and the concentration of functions in a small number of major urban centres create real spatial pressure. The dual-use character of critical infrastructure partly reflects resource constraints at the time these systems were built. Path dependencies created by decades of military investment in urban centres are not costlessly reversible, a pattern equally visible in the Futenma and Yongsan cases discussed above. These are genuine considerations that deserve acknowledgement.
The evidence does not, however, support treating these conditions as necessarily unavoidable, neither in Indonesia nor in the comparative cases surveyed throughout this section. The foundational problem of spatial constraint is not geographic pressure but the absence of civilian protection as a planning variable across regulatory layers, including spatial planning systems. For example, on infrastructural interdependence, there is an absence of cascading risk assessment requirements in Indonesia’s RRWP classifications. On path dependency, the defence risk management framework under Minister of Defence Regulation No. 17 of 2021 provides institutional language for identifying and managing risk: whether civilian risk from co-location is incorporated as a category within that framework is a governance choice, not a fixed limitation.Footnote 103
No single decision or actor produces these outcomes that Article 58 aims to prevent; rather, they emerge from the cumulative effect of governance choices made across multiple sectors and time horizons. The spectrum between genuinely unavoidable and governance-produced conditions is visible across the cases examined: certain geographic realities and historical investment decisions do place some constraints closer to the unavoidable end. Nevertheless, our predominant finding is that the conditions which narrow the feasibility space are often institutionally produced, and are therefore open to intervention. Feasibility has, in this case, become less a question of whether segregation is possible and more a question of what level of civil–military risk is considered acceptable within a framework of conditional compatibility. That framing, as the following section argues, is precisely what requires reconceptualization.
Reconceptualizing “feasibility” as a legal-spatial construct
Conceptualizing Article 58’s feasibility clause as an operational limit that arises at the moment of conflict is insufficient. Our discussion in the previous section has demonstrated that in the context of co-location, what is subsequently described as “infeasible” often results from legal decisions, spatial planning, infrastructure integration and institutional compromises that have been at work long before conflict occurs. Feasibility is therefore a question not only of what States can do when war is under way, but also of how States have previously shaped the space that determines those options.
This is precisely where the concept of feasibility requires reconceptualization. If feasibility is read only at the moment of conflict, States can assert that separation is impossible because the city is already dense, infrastructure is already interconnected, and defence facilities have long been located within civilian space.Footnote 104 Such assertions may be factually accurate, but they are analytically incomplete. The four drivers of co-location discussed in the previous section show why: by the time conflict arises, the feasibility space has largely been determined by prior governance logic, long before any military-operational decision is made. Conceptualizing feasibility as the simple question of “What is feasible now?” therefore stops at the end state without explaining the process which produced that condition.
This paper’s framework argues that it is necessary to consider that such historical embeddedness is often itself the cumulative product of prior governance choices, rather than an immutable constraint. Passive precautions carry an antebellum dimension that demands long-term planning and State foresight.Footnote 105
We therefore argue that feasibility should be understood instead as a legal-spatial construct. It is legal because it is shaped by norms, regulations, mandates and planning procedures, and is spatial because its boundaries are determined by spatial distribution, density, facility location, infrastructure, and land-use patterns. It is not a purely military concept, nor is it a purely technical one. It sits at the intersection of IHL, spatial planning, infrastructure governance and State administration.
This reading does not mean that every instance of co-location automatically constitutes a violation of Article 58. As also shown in the previous section, many examples also exist of factors causing co-location that are genuinely unavoidable; expecting States to overcome such unavoidable causes would, by definition, be unreasonable. The reconceptualization of feasibility that we propose does not require States to do the impossible, but instead invites us to consider more critically where States still retain room for action before conflict begins.
Recommendations for policy intervention
The mitigation recommendations that follow should not be understood as a separate list of solutions; they must emerge as direct consequences of the reconceptualization of feasibility developed in the previous section. If feasibility is a legal-spatial construct, then interventions must also be legal-spatial in character, reforming how space is planned, how defence functions are incorporated into zoning, how dual-use infrastructure is assessed, how institutions coordinate and how civilian risk is incorporated into defence planning. The following four intervention points correspond directly to the four structural drivers identified in the above section on “Structural Causes of Co-Location”. Furthermore, to make these intervention points more concrete, we will illustrate some ways in which they could be implemented in practice in the Indonesian case.
Spatial planning
If the problem is spatial constraints arising from urban expansion and the overlay of defence functions, then the appropriate intervention is not the total relocation of military installations (which is often unrealistic), but the incorporation of co-location risk into zoning guidelines, land-use regulations, and special provisions governing defence areas. This is consistent with the general role of spatial planning as an instrument for controlling spatial utilization, but that function needs to be extended to include civilian risk in conflict scenarios as part of the planning calculus. In Indonesia, this would mean incorporating civilian protection from military proximity into the RTRW and RDTR frameworks as a planning variable, alongside the environmental, disaster and development risks that the spatial planning law already recognizes.
Infrastructure
If the problem is infrastructural interdependence, policy should not aim at absolute separation between civilian and military systems (which is, in most cases, unrealistic and prohibitively costly). States can instead pursue partial decoupling, system redundancy, alternative routes for essential services, and risk assessments of dual-use infrastructure such as seaports, airports, rail networks, major roads, energy systems and communications. Much of the literature demonstrates that damage to urban services can produce wide cascading effects.Footnote 106 Civilian protection must think in terms of systems, not only of objects. The goal is not to eliminate functional entanglement but to reduce its uncontrolled consequences.
Institutional coordination
Fragmentation cannot be resolved simply by declaring that coordination is needed. Effective implementation requires institutional mechanisms capable of linking IHL obligations with spatial planning, defence planning, infrastructure governance and disaster risk management. Existing national coordination bodies may provide an important institutional foundation, but their effectiveness depends on whether they can move beyond legal harmonization to facilitate genuine cross-sectoral decision-making. In Indonesia, the National Committee on IHL, which involves multiple ministries and institutions including the National Armed Forces, and which is coordinated by the Ministry of Law, partially addresses this need, but the absence of a national spatial planning authority from its structure shows that IHL coordination has not yet been connected to spatial planning, defence planning and infrastructure governance. The challenge is not merely to translate IHL into domestic law, but to ensure that its precautionary obligations carry policy traction within the planning system and across the institutional sectors that produce co-location.
This recommendation on the importance of institutional coordination confirms a broader principle that underpins one of the main raisons d’être for establishing national IHL committees – i.e., that maintaining coherence and coordination between ministries, institutions and stakeholders is a key requirement for effective IHL implementation.Footnote 107 Indeed, the Global Initiative to Galvanize Political Commitment to International Humanitarian Law (Global IHL Initiative) strongly encourages that States build closer working relationships between national IHL committees and key government institutions in order to ensure that matters relevant to IHL application are identified and raised in a timely fashion.Footnote 108 This coordinating function is particularly crucial for points for improvement that may only be visible through a cross-disciplinary or interministerial lens – as is the case for co-location, as argued in this paper. As such, pursuing greater representation and integration of national IHL committees in the relevant decision-making spaces may prove a particularly effective measure to counteract this third driver of co-location.
Defence risk management
Existing defence risk management frameworks in many States already require risks to be identified, assessed, analyzed, monitored, managed, mapped, periodically reviewed and reported, providing an appropriate institutional entry point for integrating IHL considerations into defence planning. They further require that risk awareness be incorporated into organizational decision-making. This could readily serve as an entry point for incorporating civilian co-location risk into the defence system, provided that this specific risk is added as a recognized category. The critical question, in Indonesia and in comparable frameworks elsewhere, is therefore not whether defence institutions possess risk management systems, but whether civilian risk arising from civil–military co-location is recognized as a distinct category of risk capable of being identified, measured, monitored and mitigated through existing planning and decision-making processes, rather than remaining an implicit background condition of operational planning.
Steps forward
This paper has argued that the widespread co-location of military objectives and civilian populations in urban environments cannot be understood, let alone mitigated, if feasibility under Article 58 of AP I is treated solely as an operational constraint assessed as hostilities are ongoing. By tracing how “infeasibility” is frequently produced through patterns of spatial development, infrastructure design, institutional fragmentation and political-economic choices, we have shown that many conditions invoked in the moment as limiting the possibility of segregating civilians and military objectives are the cumulative result of peacetime governance and policies, rather than fixed exogenous facts. The four-driver framework – comprising spatial constraint, infrastructural interdependence, institutional fragmentation and political-economic priorities – reorients the discussion towards structural mechanisms that generate co-location. Reconceptualizing feasibility as a legal-spatial construct, rather than a narrow technical or military notion, makes visible the ways in which law, planning and administration jointly delimit what is “possible” when conflict breaks out.
On this basis, the paper has advanced a constructive reframing of the passive precautionary obligation. Distinguishing genuinely unavoidable constraints from those produced by prior governance choices opens up an antebellum action space that meaningfully strengthens civilian protection. The Indonesian case not only serves as an empirical example, but also tests the conceptual utility of our three-step diagnostic model. The analysis has shown that the first step (identifying operative structural drivers) is achievable through regulatory analysis. The second step (tracing root causes to distinguish unavoidable constraints from preventable governance failures) produces findings that are both analytically specific and practically actionable. The third step (linking diagnosis to targeted intervention) demonstrates that the feasibility space is not fixed but can be expanded through deliberate legal, spatial and institutional choices.
The model is, in this sense, scalable. It can be replicated in other State contexts to identify the relevant structural drivers and root causes specific to those settings, contributing to a gradually expanding comparative framework for understanding how passive precautions can be made more operationally meaningful in urbanized environments. We recommend that researchers and policy-makers from different States apply this diagnostic framework to their national contexts to craft targeted policy interventions and identify locally specific root causes, ultimately contributing to improving civilian protection overall.
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