I. Introduction: The end of liberal euphoria

Liberal euphoria about a ‘triumph’ of democracy following the end of the Cold War has been replaced by disenchantment, scepticism or fear about the future of democracy and the liberal world order. Major institutions and projects associated with the liberal world order are regarded to be in crisis: globalised financial capitalism, democracy promotion, liberal peacebuilding, NATO, the European Union, ‘the West’, the responsibility to protect. Narratives of doom and gloom have replaced the liberal self-confidence of the 1990s. The recent editorials of Global Constitutionalism have referred to so many instances of political violence, illiberal backlash and threats to democracy around the world that the ‘globalization of the constitutional trinity’ of human rights, democracy and the rule of law has become more questionable than ever in the last decades. Jeffrey Dunoff et al. (2015: 10–13) have critically engaged with the progressive narratives that often underlie accounts of international law and also of global constitutionalism and pointed to the contingent nature of global constitutionalism. Two years later, the journal editors still reflect on the huge challenges for the project of global constitutionalism, especially with regard to the ‘end of the “West”’ and the liberal order, but still retain an element of optimism: ‘[…] the story is unlikely to be the demise of Global Constitutionalism, rather than a significantly more complex story in which elements of demise and decay are complemented by resistance, reconfiguration and innovation’ (Kumm et al. Reference Kumm, Havercroft, Dunoff and Wiener2017: 4).

Remarkably enough, with the election of President Donald Trump in the USA and the ‘Brexit’ vote in the UK, the two countries that invested so much in the establishment of the ‘liberal order’ after the end of the Second World War, now act as spearheads of its dismantling. The journal’s 2018 editorial analysed President Trump’s domestic and foreign policy decisions as a ‘global constitutional breaching experiment’. A quite optimistic interpretation of the consequences of these disruptive policies is that these attempts and acts of norm-breaking might render the norms stronger in the end – due to strong opposition and vocal responses (Havercroft et al. Reference Havercroft, Wiener, Kumm and Dunoff2018: 7–13). However, this interpretation expresses exactly the progressive narrative that might blind ‘our’ eyes towards historical ruptures taking place and that might serve as elements of a new world order.

(Some) ‘Western’ actors within the USA and Europe now proudly exhibit their contempt for liberal norms and values and for international treaties and international organisations. In this context, Oona A. Hathaway and Scott J. Shapiro have published a remarkable and topical book that seeks to ‘prove’ the invaluable importance of international treaties and law for containing violence. The Internationalists: How a Radical Plan to Outlaw War Remade the World (Hathaway and Shapiro Reference Hathaway and Shapiro2017a) offers another variant of a progressive narrative of international law in which the 1928 Peace Pact (‘Kellog–Briand Pact’) plays the central role as international (power) game changer with tremendous repercussions for the contemporary world order. In contrast to a widespread interpretation of the Peace Pact as a naïve or useless political endeavour, the authors ascribe enormous long-term consequences to the treaty:

Hathaway and Shapiro retell the history of some 400 years by focusing mainly on the perspectives, struggles, deeds and failures of white male scholars, intellectuals and politicians in the Global North.^{Footnote 1} The authors distinguish between an ‘old world order’ (established over the 17th century, culminating in the beginning of the First World War in 1914 and coming to an end in the Peace Pact of 1928), a very violent ‘transformation’ period, and the establishment of a ‘new world order’ from roughly 1945 onwards. The legal structure of the old world order was marked by states’ privilege to use force and related legal rules such as a right of conquest, a ‘license to kill’, gunboat diplomacy and neutrality as impartiality (Hathaway and Shapiro Reference Hathaway and Shapiro2017a: 97). The legal structure of the new world order is reconstructed in the book as a kind of ‘photo negative’ of the old world order: In its centre is the prohibition of the use of force and related legal rules such as the illegality of conquest, aggression as a crime, prohibition of coerced agreements and the permission of sanctions (2017a: 303).

The book has many strengths, including the elaboration of a provocative thesis that traces numerous changes back to the – often ridiculed and usually neglected – 1928 Peace Pact and making visible the individuals and the intellectual struggles behind treaty texts and formative events. In the following, I will highlight several issues that, from a political science/International Relations (IR) perspective, are surprisingly neglected in the book.

II. The role of weapons and technological developments

Hathaway and Shapiro suggest a strong causal claim about the long-term impact of the 1928 Peace Pact. It is not surprising that this claim has provoked critical responses by commentators. Stephen Walt (Reference Walt2017), for example, wrote:

Hathaway and Shapiro (Reference Hathaway and Shapiro2017b) explained in a brief reply how they conceive of the ‘causal’ impact of international law: ‘[Walt’s] reaction reveals a misunderstanding about how law works. When it is most effective, the law doesn’t induce states to act contrary to incentives; it changes those incentives themselves.’ The change of incentives through law would apply to both stronger and weaker states.

While this is plausible, there are other powerful factors that have changed the incentives for states in conducting their foreign policies. There are many studies in International Relations dealing with the question of why the number of interstate wars has declined so significantly. Hathaway and Shapiro (2017a: 332) correctly note ‘the advent of nuclear weapons, the spread of democracy, and more robust global trade’. However, the authors partly dismiss the relative importance of these factors and argue that ‘the missing element in all of these explanations is […] the outlawry of war that began with the Peace Pact’ (2017a: 333).

Neorealist IR scholars usually point to bipolarity and nuclear deterrence; liberal IR scholars focus on the role of democracy, international organisations and economic interdependence; and social constructivist scholars emphasise the role of norms and identity (Waltz Reference Waltz1979; Risse-Kappen Reference Risse-Kappen1995; Russett and Oneal Reference Russett and Oneal2001; Rauchhaus Reference Rauchhaus2009: 259). It is remarkable that Hathaway and Shapiro mention nuclear weapons merely on three pages in their book although there has been a lively debate over the impact of nuclear deterrence on international conflicts. To what extent the advent of weapons of mass destruction, especially nuclear weapons, have changed states’ cost–benefit calculations remains a controversial issue (Jervis Reference Jervis1988; Sauer Reference Sauer2015: 8–24; Geller Reference Geller2017).

One can roughly distinguish three IR schools of thought on nuclear deterrence (Geller Reference Geller2017): The first, labelled ‘nuclear revolution’ theory, maintains that the high and rapid destruction effects of nuclear weapons provide strong incentives for nuclear-armed states to avoid violent escalations in their interactions. A second school focuses on crisis behaviour of nuclear-armed states below the level of major war and analyses their risk behaviour and brinkmanship tactics; a third school claims that nuclear weapons are irrelevant for the decline of major interstate wars. John Mueller (Reference Mueller1989), for example, argued that nuclear weapons do not substantially differ in their deterrent effect from conventional military forces and that developed countries will fight neither conventional nor nuclear wars since they have witnessed the vast destructive effects of both the First and the Second World Wars. Empirical research shows that the influence of nuclear weapons on state interaction between nuclear-armed states and between other dyads is difficult to determine and that it can also change due to prior experiences. Quantitative research on the ‘nuclear peace’ hypothesis suggests that nuclear weapons ‘do not affect the frequency of conflict, but they do affect the timing, intensity, and outcome of conflict’ (Rauchhaus Reference Rauchhaus2009: 271). Geller (2017: 25) draws three conclusions from existing empirical studies: First, wars among nuclear-armed states are improbable. However, the so-called ‘Kargil War’ between the two nuclear-armed states India and Pakistan in 1999 is a remarkable exception. Second, crises among nuclear powers ‘have a higher probability of escalating – short of war – than do crises for asymmetric or nonnuclear dyads’. Third, with regard to the interactions of nuclear and nonnuclear states, aggressive behaviour by the nonnuclear state has not been impeded in the past.

Social constructivist research on the norm conflicts and norm dynamics in the field of arms control and disarmament may be even more relevant to Hathaway’s and Shapiro’s argument. According to some scholars, a ‘taboo’ against the use of weapons of mass destruction, especially of nuclear weapons, developed for a majority of states in international society during the 20th century after their use in the Second World War against Hiroshima and Nagasaki (Tannenwald Reference Tannenwald2007; Sauer Reference Sauer2015). As is well known, this does not imply that biological or chemical weapons have not been used since nor that nuclear weapons have not been tested – nor that such a ‘taboo’ could not erode over time (Sauer Reference Sauer2015: 33–6) – but the international regimes of arms control and disarmament are especially relevant international treaty arrangements. The multilateral regulation of the most lethal weapons available to humankind concerns the core interests of state security and also involves important issues of justice in international society (Müller and Wunderlich Reference Müller and Wunderlich2013). The Treaty on the Non-Proliferation of Nuclear Weapons (NPT, effective since 1970) divides the member states into five recognised possessors of nuclear weapons and those that are not allowed to acquire nuclear weapons. Although the nuclear weapon states have not fulfilled their obligations regarding disarmament and although a number of states have in the meantime acquired nuclear weapons, the unequal nuclear order that the NPT has established has been nearly universally accepted.

The stigmatisation of the use of nuclear weapons (or chemical weapons) shapes state identities as ‘civilized nations’ (Tannenwald Reference Tannenwald2007: 46). Non-compliance with such a strong norm can be sanctioned by excluding such actors from the international community. The labelling of a state as a ‘rogue state’ is a notorious form of ‘outcasting’ that does not play a role in Hathaway’s and Shapiro’s (2017a: 371–95) long chapter on ‘outcasting’ as an ubiquitous form of punishing rule breakers in the ‘new world order’. They consider outcasting as a non-violent form of excluding an actor from the benefits of community membership: ‘like force and threats of force, outcasting constrains choices. But it does so without the cruelty and destruction that normally accompany war’ (2017a: 395).

While this certainly applies to many instances in international politics, outcasting a state or non-state actor by labelling it a ‘rogue’ or ‘evil’ often legitimates the use of force against the stigmatised actor. The emergence of the US ‘rogue states’ discourse after the end of the Cold War shows that (only some) states become ‘rogues’ if they seek to acquire and proliferate weapons of mass destruction. Although states can be ‘de-rogued’ again (Libya serves as an example), such stigmatising labels prove as sticky and can turn states into ‘pariahs’ and ‘outlaws’ of the international community – which, in its turn, also has repercussions on such states’ self-perception and foreign policy choices (Geis and Wunderlich Reference Geis and Wunderlich2014; Wagner, Werner and Onderco Reference Wagner, Werner and Onderco2014).

III. The political culture aspect: Populations, publics and normative change

It is, of course, very important to tell the stories of influential scholars, intellectuals and politicians in shaping crucial moments of history. To what extent notions of the legitimacy of war or the outlawry of war were shared by the respective populations and reference groups in societies is not explicitly dealt with in the book. On several pages, the authors briefly mention – without elaborating – public opinion, people or media that would support or not support a specific idea or political measure. A particularly instructive section of the book is the one on the so-called war manifestos.^{Footnote 2} Such a manifesto is a public document, issued by a sovereign against another sovereign, which contains the reasons for going to war (Hathaway et al. Reference Hathaway, Holste, Shapiro, Van De Velde and Wang2017). The analysis of more than 400 manifestos, produced between 1492 and 1945, yields a revealing collection of ‘just causes’ for war over the centuries (Hathaway and Shapiro Reference Hathaway and Shapiro2017a: 42–3). While some of these causes have gone out of fashion, such as wife stealing, collection of debts or enforcement of succession and other hereditary rights – a number have reappeared in new guises and variations in justification discourses to date, such as self-defence, enforcing treaty obligations or humanitarian considerations (cf. Finnemore Reference Finnemore2004).

Hathaway and Shapiro make the important point that ‘Manifestos matter precisely because they are propaganda. The function of propaganda is to persuade. We can therefore tell what reasons people usually found persuasive by examining the reasons that propaganda offered to persuade them’ (2017a: 42; emphasis in original). However, they do not provide a further theoretical or methodological underpinning of this resonance claim that is quite familiar to social constructivist researchers today, but that would not necessarily be linked to European kings or emperors in the 15th or 16th century. Contemporary social constructivist research on parliamentary discourses assumes such a resonance effect in modern democratic public arenas – the intriguing claim that Hathaway and Shapiro advance is that this also applies to pre-modern, highly non-democratic political systems and social settings.

Liberal explanations of the decline of interstate wars often refer to the ‘democratic peace’ thesis. The empirical finding that democratic states have rarely fought each other in history has inspired an extensive liberal research programme in IR, emerging since the early 1990s, often citing Immanuel Kant’s famous 1795 essay on ‘Perpetual Peace’ as its philosophical foundation (e.g. Russett and Oneal Reference Russett and Oneal2001). Advocates of the ‘democratic peace’ claim that democratic institutions and (liberal) norms have a pacifying influence on the foreign policy of democratic states. Citizens are considered to be sensitive to the risks and costs of war and hence rather reluctant warriors, except for situations of self-defence; democratic leaders, interested in being re-elected, will respect their citizens’ majority preferences. However, while democratic dyads are peaceful, democracies are often involved in wars and military actions with non-democracies (Risse-Kappen Reference Risse-Kappen1995). In addition to domestic level explanations, liberal proponents of the ‘democratic’ or ‘Kantian’ peace also argue that international organisations and economic interdependence have a pacifying effect on states so that ‘all good things go together’ in this ‘virtuous circle’ of state interactions (Russett and Oneal Reference Russett and Oneal2001: 24–33).^{Footnote 3}

Hathaway and Shapiro’s research on war manifestos is very intriguing from a ‘democratic peace’ perspective since one would assume that elected democratic leaders and members of parliament face an increased pressure to justify an intended military action vis-à-vis their constituencies, given risk-averse citizens reluctant to take up arms. Some democratic states do engage in the use of military force, and content analyses of their public discourses confirm that democratic political elites usually need to justify these decisions (Geis, Müller and Schörnig Reference Geis, Müller, Schörnig, Geis, Müller and Schörnig2013). One can infer from domestic analogies on the use of force within democratic polities that there exist procedural and substantial ‘legitimising requirements’ that also structure the external use of force by democracies (Müller and Wolff Reference Müller, Wolff, Geis, Brock and Müller2006: 61). The use of force is not prohibited per se within democracies, but its legality and legitimacy are made contingent upon the respective legal order and politico-cultural norms of the polity. By analogy, one can expect that decisions on war participation must, first, be in accordance with procedural requirements, i.e., meet procedural standards of domestic lawful decision-making and of international law, and, second, must be justified publicly with ‘good reasons’ which are accepted as legitimate by the majority of the respective democratic public. Political elites and citizens alike can also develop preferences favouring the use of force in a given conflict, i.e., there are some justifications that are accepted as legitimate reasons for war (Schörnig, Müller and Geis Reference Schörnig, Müller, Geis, Geis, Müller and Schörnig2013).

Content analysis of parliamentary speeches in democracies is but one social science method to identify the arguments used by political elites to legitimate their decisions. The analysis of speech acts uttered by a political actor to justify a particular action does not always provide reliable information about the motivation behind the actor’s policy choice, as actors can always act strategically when stating their motivation for a particular action or justifying their position on a particular issue. They can simply lie about their motives. By drawing on speech act theory, it is possible to infer what the speaker thinks his audience is going to accept as a valid argument. Speech act theory emphasises the performative dimension of the utterance (Searle Reference Searle1969): The speaker intends to achieve a particular purpose. Political speech acts aim at generating specific and diffuse support (Easton Reference Easton1965). Specific support means assent to the particular political decision in question. Diffuse support includes the appreciation of the speaker beyond the special political action in question.

Politicians ‘belong to a community whose constitutive values and norms they share’ (Schimmelfennig Reference Schimmelfennig2001: 62) – or at least are familiar with. Consequently, even if actors have private motives or interests in pursuing a particular course of action, they will at least try to relate their action to an accepted argument within the range defined by the constitutive values and norms mentioned above. From this perspective, it is very likely that democratically elected agents who have to justify their actions or intentions publicly in order to reach consent submit ‘resonant’ arguments, i.e., arguments which they think will correspond best to the value orientations and interests of their constituents. This applies in particular to parliamentary debates where speakers have to justify their positions to the public and defend them against the opposition (Schörnig, Müller and Geis Reference Schörnig, Müller, Geis, Geis, Müller and Schörnig2013: 34–8).

How about the public resonance of war manifestos in the 15th, 16th or 17th centuries: Who were the popular reference groups for leaders publishing such manifestos? How were those manifestos circulated, received and consumed in social settings and political entities that had no resemblance to the modern democratic nation-state? It is an important finding for ‘democratic peace’ research that autocratic leaders (putting it, rather moderately, in contemporary political science categories) have also been engaging in justifying their wars and military actions over the centuries.

Why such ‘just causes’ for war can resonate at a certain time and why later on the outlawing of war marked such a crucial break requires the investigation of political cultures – norms, values, attitudes – of a respective society. The focus of The Internationalists on influential individuals in academia and politics renders invisible the cultural underpinnings of norm change. The diplomatic acts and international treaties of outlawing war cannot be fully appreciated without considering the societal and cultural changes of the later 19th century and the first half of the 20th century in a number of the countries that provide the stages for the selected elite norm entrepreneurs starring in the book (cf. Mueller Reference Mueller1989: 17–36; 1991: 52). The important role of international peace movements and of cultural elements influencing the social imaginaries of societies – such as novels, paintings, films and photographs about horrifying war experiences – could have provided the necessary contextualisation of the fascinating stories of the book.

As is rather noted in passing in the book, the gradual rejection of war as an instrument of ‘civilized’ politics has also come about through the experiences of and reflections about the extremely destructive large-scale wars in the 19th and 20th century. In addition, the emergence of political publics, an expanding level of education and new forms of media made it possible to communicate the horrors of war to larger segments of societies. To what extent societies of the Global North have undergone processes of deep-rooted ‘civilianization’ and ‘learning’ from prior experiences of excessive violence is certainly a matter of controversy – and all that has been learned can be ‘unlearned’ and undone again, i.e., such processes can be reversed. This notwithstanding, John Mueller’s much-cited book Retreat from Doomsday: The Obsolescence of Major War (1989) provides arguments that can be read in some ways as complementary to Hathaway’s and Shapiro’s line of argument; in some ways it makes even bolder statements. Mueller (1991: 44, 47–52) also emphasises that ideas matter (who would dispute this, actually?) and that large parts of populations have gradually changed their attitudes towards war through painful experiences, especially the traumatic experience of the First World War.

In contrast to some essentialising treatises on aggression, violence and war as inherent anthropological features of human beings, Mueller underlines that war is an institution – like duelling or slavery – that has emerged in human history, but that could also disappear as an institution. In contrast to Hathaway and Shapiro, however, he does not consider international organisations or international law as central mechanisms for changing incentives in the international power game – but places a remarkable (and unwarranted) trust into people’s attitudes and perceptions (Mueller Reference Mueller1991: 50).

Since the societies of the ‘democratic peace’ countries have now enjoyed a relatively long period of peace, one might well ask whether the fading traumatic memories of the World Wars will have their strong impact also on some future generations – when eyewitnesses have died and when World War memory politics might lose political and societal clout. In addition, the changing character of war and warfare (Strachan and Scheipers Reference Strachan and Scheipers2013; Barkawi article in this Agora) has generated military strategies and warfare practices since the 1990s that render war experiences rather intangible (if not invisible) to Western societies at large, such as the use of drones, fear of ‘cyberwar’, the restructuring of Western armies to professional armies or an outsourcing to private security and military companies.

IV. Still living in a ‘new world order’?

The Internationalists is nicely structured into three larger parts: the ‘New World Order’ (Part III) is depicted in strong contrast to the ‘dark’ and violent ‘Old World Order’ (Part I), with a ‘transformation’ period in between (Part II). The stylised contradistinction of these ‘bright’ and ‘dark’ world order periods has been rightly criticised in the contribution by Oliver Diggelmann (in this Agora). I would like to interrogate the labelling of a ‘new world order’ from some different angles: First of all, why should we label an order that has now existed for more than 70 years still a ‘new’ order? What is more important, I would question if ‘we’ currently still live in the same ‘type’ of world order that is depicted in the chapters of Part III. This raises a more general epistemological point: Which type of world order is in existence right now? We can only tell for sure with the benefit of hindsight, and actors from different parts of the world will probably describe ‘the world order’ in differing categories – but as contemporary witnesses, we have severe cognitive problems in assessing short-term, medium-term and long-term effects of certain political decisions and socio-political developments.

Social orders are not static, uncontested sets of norms and rules. Rather, each normative order faces challenges and challengers, and self-proclaimed or appointed guardians of an order engage in ordering practices and seek to delineate who can be considered a legitimate member of a certain order and who is (to be) excluded. Many Western scholars have labelled the post-Cold War order ‘liberal’ – although there have existed varieties of liberalisms throughout history and although there has never existed one ‘pure’ liberal model of world order (cf. Dunne and Flockhart Reference Dunne and Flockhart2013). Liberal democracies, under the leadership of the liberal hegemon USA, have engaged in many military interventions, publicly justified by ‘liberal’ reasons. During the Kosovo War, the then British Prime Minister Tony Blair summed up the core ideas of the so-called ‘liberal interventionism’:

Since Hathaway and Shapiro retell the development of the international legal system and the international order with a focus on the use of force, it is more than surprising that the use of military force by liberal democracies is noted only in passing in Part III: Iraq, Kosovo, Afghanistan, Syria (‘Global Coalition against Daesh’), and several military interventions in African states such as Libya, Mali, Côte d’Ivoire or Central African Republic. Some of these missions have been conducted predominantly by liberal democracies, some in partnerships with other states, some have had a UN mandate, some have not.

A related issue is the use of so-called ‘coercive diplomacy’ by liberal democratic states. As Hathaway and Shapiro rightly note, ‘gunboat diplomacy’ has become obsolete in the new world order. However, in some cases where the UN Security Council has not (yet) produced a mandate for military interventions, a number of democratic leaders and members of parliament do threaten the use of force including through a military ‘show of force,’ the deployment of troops or ordering of military manoeuvres near conflict territories. US President Obama’s famous statement of a ‘red line’ that the Syrian Assad government would cross by using chemical weapons or President Trump’s threat of ‘fire and fury’ vis-à-vis the North Korean leader Kim Jong-un are more recent examples of such rhetoric. In an analysis of pre-war discourses on the Gulf War 1991, the Kosovo War 1999 and the Iraq War in 2003 in seven democracies, we found that a surprisingly large number of parliamentarians accept the necessity of a show of military force to back ‘coercive diplomacy’ and to enforce compliance by military means. At first glance, this argument does not necessarily imply military conflict: It is the aim of coercive diplomacy to impose compliance by demonstrating – but not actually using – one’s military capabilities, i.e., to send credible signals to the adversary and demonstrate unified resolve (Schultz Reference Schultz2001: 23–116).

But deploying troops in a crisis theatre is a risky business and can be understood as the first step on a slippery slope to war: Once the troops are on site, a countdown starts since they cannot be deployed abroad indefinitely due to complex logistics and high costs. Simultaneously, political pressure mounts to accept only full compliance as the face-saving solution. Withdrawal without compliance is the least acceptable option, raising the likelihood of the actual use of force. Empirically, coercive diplomacy has failed in most cases, and has led to war in the majority of cases (Art and Cronin Reference Art, Cronin, Crocker, Hampson and Aall2007). In conclusion, deciding in favour of threatening force often means actually choosing the war option in the long run. While many parliamentarians accept this connection, some – especially very early in a conflict – do not see (or refuse to see) that they are stepping onto a slippery slope.

Why does the use of force by liberal democracies not appear prominently in The Internationalists? In a legal sense, one might not be able to categorise these military actions as ‘wars’. In a political science database such as the Correlates of War (see Barkawi article in this Agora), some of these military actions might also escape categorisation as ‘wars’. Foggy labels such as ‘humanitarian intervention’, ‘policing actions’ or ‘stabilisation missions’ veil the ‘war-like’ actions that are implied. They de-emphasize the fact that the use of force justified by ‘good causes’ can nevertheless be experienced as ‘war’ and is often discussed as ‘war’ in publics (cf. Geis, Müller and Schörnig Reference Geis, Müller, Schörnig, Geis, Müller and Schörnig2013).

The use of military force by democracies has shaped the world order tremendously since the 1990s and is in itself a manifestation of world ordering practices – not of conquering territories – but of attempting to spread one’s own notions of statehood, democracy, market economy and human rights to other parts of the world. These attempts often failed. The heyday of the ‘liberal interventionism’, a manifestation of liberal self-confidence or hubris in the 1990s, might thus be over. The liberal hegemony of the USA and its NATO allies is in decline and democratic publics have become increasingly ‘intervention wary’. The concept of ‘liberal peacebuilding’ as such is in crisis (Chandler Reference Chandler2017).

The current debates on a transition to a multipolar world order and a ‘new regionalism’ (Acharya Reference Acharya2014) suggest a gradual transformation of the world order in which influence and authority migrate from the United Nations Organization to regional hegemons and regional organisations. Such a transformation of the world order might also be indicated by altering patterns of justifying military actions. Two major lines of justification have become especially relevant since the 1990s: One line has evolved around human rights norms and the concept of human security. The ‘humanitarian interventions’ of the 1990s and the emergence of the ‘responsibility to protect’ implied a redefinition of state sovereignty. States that are not able or not willing to protect their own citizens risk external forcible intervention. The second line of justification has evolved around state security in the wake of the US-led ‘global war on terror’: counter-terrorism and counter-insurgency strategies in order to fight non-state armed groups appeal to both democratic and non-democratic states so that security cooperation between democratic and autocratic governments have become more frequent. Chinese, Russian, Saudi-Arabian and Nigerian governments can unite with ‘Western’ governments under the notoriously broad umbrella term of ‘counter-terrorism’. In contrast to humanitarian-oriented intervention practices that interfere with state sovereignty and autocratic governments, contemporary counter-terrorism and counter-insurgency measures often strengthen autocratic governments – but tend to undermine human rights norms (Heller, Kahl and Pisoiu Reference Heller, Kahl and Pisoiu2012; Moe Reference Moe2018).

Considering the altering security practices of democratic and autocratic states, new forms of security cooperation arrangements, technological advancements such as drones and the cyberspace, altering justifications of the use of force, it is about time to rewrite Part III of the fascinating book on The Internationalists. Outlawing ‘conventional’ interstate war is not enough to maintain international peace in the 21st century.