The “policy science” of civil wars, which emerged in the early 1990s, included deeply embedded assumptions about the nature of the international political system. It was taken for granted that the United States would remain the strongest power by a wide margin, and that it would lead a liberal coalition that included virtually all the other strong states in the world. Some students of international politics believe that the nature of the system is changing. Though the United States is likely to remain much more powerful than its global competitors, several consequential powers have emerged to challenge U.S. leadership and produce a multipolar system. As power begins to even out at the top of the international system, the influence of middle powers may also grow. This new constellation of power seems likely to magnify disagreements about how states suffering civil wars should be stabilized, limit preventive diplomacy, produce external intervention that will make for longer and more destructive wars, and render settlements more difficult to police.

Over the last seven decades, civil war has become much more prevalent than interstate war as a form of organized military conflict. On the average, 2.2 new civil wars break out every year, with nearly fifty such conflicts ongoing today.1 Since the end of the Cold War, scholars, diplomats, and soldiers have poured enormous energy into understanding the causes, courses, and consequences of civil wars, even as coalitions of outside powers have intervened in civil wars to terminate them altogether, or at least to ameliorate the collateral damage. Much of this thinking and practice emerged during what international relations scholars dubbed “the unipolar moment,” the unusual concentration of all forms of power in the hands of the United States in the 1990s. This concentration of power enabled, though did not demand, U.S. efforts to manage civil wars. It also created a kind of gravitational force that subtly affected theories of conflict management. The possibility that another great power would be a player in these civil wars, an opponent of negotiated settlements, or a spoiler in the aftermath of such settlements was seldom considered. Because some knowledgeable observers believe that the unipolar moment is waning, this essay first discusses uni-, bi-, and multipolarity, and how international politics may vary as a consequence of different structures of power. It then deduces the plausible effects of these different structures on the three phases of potential external intervention in civil wars: prevention, termination, and peace enforcement. It draws exemplary material from the Balkan Wars of the 1990s and the ongoing Syrian Civil War. In general, if multipolarity is in our future, then I believe external intervention to manage civil war is going to become much more difficult.

Scholars, policy analysts, and policy-makers have used “polarity” as an organizing concept since at least the beginning of the Cold War. It captures the intuition that the distribution of power in the international political system affects the behavior of the states that compose it, and that though there may be many nation-states in the world, power tends to cluster at the top. The distribution of power is taken to be somewhat measureable and, for meaningful periods, to be fixed in character. In modern times, the size and dynamism of an economy of one state relative to that of another is often taken as a good, though imperfect, proxy for relative power, since it is from the economy that hard power–military power–is ultimately distilled. Territorial extent, geography, population, and the level of development also matter, as does a state's willingness on a regular basis to convert these assets into military power.

Scholars often mark the birth of the modern international system with the Treaty of Westphalia in 1648, which ended the horrendous bloodletting of the Thirty Years' War and established the principle of state sovereignty.2 From then until the end of World War ii, states operated in a multipolar world, in which three or more states typically jockeyed for position on approximately equal terms. Occasionally, one state became much stronger than the rest, bid for hegemony, and was thwarted at great cost. The Cold War is usually described as a bipolar world: the power of the United States and the Soviet Union dwarfed that of the remaining states, and each was obsessed with the threat posed by the other. The emergence of the bipolar distribution of power was seen as so unusual that it prompted scholars to begin thinking about how systems of different polarity might behave differently.3 In the immediate aftermath of the Soviet collapse, scholars and pundits quickly began to describe the world as unipolar. The U.S. government's National Intelligence Council has forecast that unipolarity is on the wane, to be replaced by a new multipolar world.4

Polarity matters particularly to those international relations theorists who style themselves as “realists.” Realists argue that all states must deal with one overarching problem: anarchy. They live in a political system without an overarching authority. States must look to their own security because there is no agreed-upon global police force to call if they find themselves the victims of a crime. States thus live in a “self-help” system, and power, especially military power, is a key means of self-help. It is also the key means for despoiling one's neighbors. Power is both problem and solution. States eye one another warily, and when they can improve their own insurance–by expanding their national power or reducing the power of another–they will often do so, subject to calculations of benefit and cost. They compete particularly in the realm of national armaments, and depending on structure, in the realm of building and/or eroding alliances. Not all states will play the game. But states that fail to play the game often suffer for their abstention. As the game is constant, there are plenty of learning opportunities. The anarchical condition makes polarity a particularly important variable. In a world in which there is no overarching authority to prevent or punish the use of force, the distribution of power–the ability to use force–casts a long shadow. Realists like to say that the distribution of power, the structure of the system, “shapes and shoves.” It presents constraints and creates incentives, even for the most powerful states in the system. Structure influences state behavior, but it does not determine it.

Unipolarity is a world in which the power of one state dwarfs that of the rest. Most scholars seem to agree that the U.S. position in the 1990s is the only example we have of a unipolar system. Unlike bipolar and multipolar systems, the “unipole” faces few constraints; rather, it lives in a world of temptation. Facing little meaningful opposition, the United States was tempted to organize the world according to its own, mainly liberal theories. The order of the day was the spread of democracy and market economies, and preservation of the unusually happy power position enjoyed by the United States. Though the tremendous difference in power between the United States and others constituted a temptation, it at the same time made the United States quite secure. This introduced an element of caprice into U.S. behavior. The United States took up some causes and not others; it did not intervene in every civil war to protect liberal principles or remake governments. During the unipolar moment, the United States intervened most often in civil wars that occurred close to other existing U.S. interests. The Balkans exerted a magnetic attraction because of its proximity to nato, and Haiti became a priority because thousands of its unhappy citizens could attempt a boat trip to the United States. And the expansion of the borders of the nato alliance in Europe, while impressive, nevertheless slowed as it approached the borders of the much weakened, but still nuclear capable, Russian remnant of the Soviet Union. Though other states occasionally tried to “balance” U.S. power, or throw wrenches in U.S. projects, these states did not have many cards to play, and they knew it. They might oppose the United States in the un Security Council, or simply not show up to assist with some U.S. projects, but in general, the principal costs the United States encountered were exacted by the designated “villains” in those military interventions the United States chose to undertake, and these costs were low until the 2003 invasion of Iraq.

Unipolarity was noteworthy for the way it affected thinking about intervention. To begin, the United States or the coalitions that it led could intervene in a civil war without having to think about threats elsewhere. No one could argue that one could not afford to have troops tied down in the Balkans because those military forces might be needed elsewhere. Indeed, then–un Ambassador Madeleine Albright famously asked: what were the troops for if not intervention? Second, no one could argue that the designated villains in these civil wars were protected by other great powers, for there was no other great power to protect them. Third, the decision to intervene, and the appropriate strategy of intervention, was mainly a negotiation among like-minded middle powers: long-standing members of the U.S. Cold War camp who were themselves too weak to either oppose the United States or to force its hand. Fourth, given the tremendous U.S. superiority in military power, the United States and its coalition partners typically expected that the wars would be cheap, and that the United States would pay most of the costs anyway.

The unipolar moment also affected international norms. Norm entrepreneurs, most of them dedicated to the spread of liberal norms, seem to have presumed that power would continue to be concentrated in the hands of a liberal state. For example, those who advanced the notion of the “responsibility to protect” (r2p)–which asserts that outsiders have a perfect right to intervene in the internal affairs of other countries whose governments, in the eyes of outsiders, abuse their people–were unconcerned about the concomitant erosion of the traditional sovereignty norm. The notion that the older sovereignty norm may have helped dampen international conflict among great powers was not much discussed.

A bipolar structure of power is equally rare, and the Cold War is our only example. When two states overshadow the rest, they eye one another warily because each is the greatest threat to the other. The competition tends to become all-encompassing. As each power tries to preserve or improve its position, the other scrutinizes these moves for how they might become a threat, and how they might be exploited. Countermeasures are taken rather quickly when the other superpower seems to be up to something. In the Cold War, the competition included military means, science and technology, the accumulation of allies (despite their modest utility), and competitive interventions in civil wars. Of course, structure cannot explain everything about the intensity of the Cold War competition; the parties had vastly different ideologies and visions about how the world should work, adding energy to an already fraught situation. And the two sides confronted one another with unfamiliar but extremely frightening nuclear weapons. Fear of nuclear escalation seems to have put downward pressure on the competition: the two sides struggled for advantage but seemed mindful of the possibility of disaster. It is noteworthy that despite direct involvement in many wars, and indirect support of the opposing sides in many others, there was no direct violent clash of U.S. and Soviet forces. Finally, the bipolar nature of the competition seems to have had a strange liberating effect on each side's willingness to get involved in local conflicts. Instead of fearing that involvement in a civil war would reduce capabilities that might be needed elsewhere to oppose the other great power, these conflicts were perceived as part of the central competition. One posited reason for this is that, due to the nuclear competition, each side had a very strong interest in credibility. Thus, a fight for credibility anywhere could be viewed as contributing positively to the credibility of one's commitments to risk nuclear war worldwide.

Competitive Cold War interventions produced particularly tragic outcomes. The parties to these civil wars were rendered artificially strong by outside assistance, so the wars were more intense and longer-lasting than they might have otherwise been.5 Once they had chosen sides, the superpowers might find themselves in one of several kinds of traps. If one's preferred side fared poorly, there was a strong temptation, as happened in Vietnam and Afghanistan, to intervene directly to save one's proxy. This presented a tempting opportunity to the other superpower to add resources to its client in order to bleed its principal opponent. This was an inexpensive way to improve one's own power position. At the same time, when the two superpowers were involved directly or indirectly in a civil war, they feared escalation to direct engagements between their own forces. As both parties were major nuclear weapons states, a direct clash would produce risks and costs far in excess of anything to be gained from the civil war. Thus, the two sides tended to focus more on “not losing” than on winning, further prolonging the suffering of the civilians living in the war zone.

Multipolar systems have three or more great powers. But measuring relative power in the twenty-first century is a tricky proposition. By many measures, the United States is still comfortably ahead of its closest competitor–China–though the gap is narrowing quickly. My criteria for a great power are a large and diverse economy, capable nonnuclear forces, some ability to project power beyond borders, and nuclear deterrent forces with the ability to retaliate against a state's most plausible adversaries and maintain that ability in the face of a determined arms race. (Possession of an assured retaliatory capability is essential for a state to pursue an independent security policy in the nuclear age.) By these criteria, the key powers are currently the United States, China, and Russia. France, Britain, and India constitute a second tier of important powers. By mid-century, Russia and India will likely reverse positions. Strict parity among great powers is not a requirement for viewing a system as multipolar; historically, there has often been a very large gap between the most and the least capable “great powers.” This analysis assumes that the world is trending toward multipolarity and asks what difference it makes.

States compete for power and security in multipolar systems, but the sheer number of players changes the game. First, in multipolar systems, allies matter more than they do in other systems. With a handful of powers at the top of the global order, coalitions can often significantly outweigh the capability of any single state. Thus, though states in a multipolar world must look to their own armaments in order to be alliance-worthy, they must also look to the diplomacy of coalitions. A second property of multipolar worlds is divided attention. With many possible allies or adversaries, states will tend to see the possibility for incremental gain; for example, if State a concludes that State b is otherwise occupied with State c, that presents opportunity. Third, the fear of countervailing coalitions imposes caution. In our time, the presence of nuclear weapons imposes still further caution. Fourth, it is plausible that multipolarity mutes ideological competition. The need to make one's own alliances and undermine those of an adversary may cause states to submerge their ideological differences.

If the world is trending toward multipolarity, this should affect external intervention in civil wars. The great powers will be more concerned about other great powers, which should make civil wars generally less important to them and thus make early preventive intervention less likely. The exception to this generalization may arise when civil wars occur in regions of particular political importance for geographical, economic, or ideological reasons, such as the greater Middle East. But in these cases, great-power competition will be intense from the outset, exactly when cooperation would be most useful for prevention. When multilateral intervention is proposed in the collective interest of the international community, the principal powers will still be concerned with relative gains. This will further complicate the prospects for collaborative efforts to settle the civil war. States may still wish to involve themselves in particular civil wars, for their own selfish reasons; because the problems posed by civil wars are often local, the most proximate great powers will be the most tempted to intervene. Finally, once one great power does intervene, and if its effort goes awry, it will be tempting for others to exploit the situation to improve their own position. Other great powers may aid the opposing side simply because the opportunity to enfeeble their competition is too tempting. Alternatively, they may offer assistance to continue the intervention or offer to create a diplomatic fig leaf to cover a disengagement, at a high cost to the intervener.

A final property of the emerging multipolar world that will affect intervention lies just outside the realm of the great powers. The National Intelligence Council grounded its forecast of a multipolar world in a larger discussion of a diffusion of power: the post–Cold War spread of economic, technological, and military capabilities to states and to nonstate actors.6 Middle and small powers themselves often intervene in civil wars, especially in their own neighborhoods, and their capabilities will also grow. Their interventions can produce some of the same negative consequences as great-power interventions.

The unipolar moment plausibly affected the theory and practice of preventive diplomacy, direct intervention, and postwar settlements. First, decisions to intervene could then be made in a kind of geopolitical vacuum. The argument for nonintervention based on scarcity of resources and a concomitant fear that being tied down in a small war might make one vulnerable elsewhere to a large challenge was irrelevant. At the same time, given the great security enjoyed by the victorious Cold War liberal coalition, the security case for intervention was usually weak. The situation caused analytic attention to be focused elsewhere. The main problems became how to get great powers to pay attention to emerging civil wars and engage in preventive action of some kind. The responsibility to protect is the expression of this problem. Advocates of r2p seem to have hoped that an agreed-upon international norm would create a predisposition to act, if it seemed that a government had lost its willingness or ability to look after all of its citizens. The existence of this normative predisposition would also motivate great powers to develop early-warning indicators so they could substitute early preventive diplomacy for the use of military power later. These two strands have in some sense come to fruition. Though arguments continue on what r2p means practically, and how strong the norm is, the notion that outside military intervention is warranted in cases of extreme violence is a part of the foreign policy debate. Western intelligence agencies have tried to develop better an ability to warn of impending civil wars and of mass atrocities. Given the low interests that great powers have in most civil wars, these tools were never destined to be particularly effective.7 But a multipolar world will likely make them even less effective.

Preventive diplomacy often either does not occur, or is ineffective. Attention then turns to how outside powers can help bring a civil war to an end. Once a civil war begins, the combatants hope to decisively defeat one another and do so quickly. Such splendid victories are rare, and it is more often the case that the wars settle into attrition battles.8 In such battles, the combatants must “measure” relative power and relative will. This helps them assess the future costs of fighting relative to their perceived benefits and the odds of achieving them. Analysts suggest that “hurting stalemates” can develop: a combination of high costs and perceived futility that will make the warring parties more prone to negotiate, if given a nudge by outside powers, and assurances that outsiders will police any agreement to prevent defection.

The values that underlie the r2p norm suggest that it can be difficult for outside observers to wait for a hurting stalemate. This has led some analysts to suggest that outsiders should intervene militarily to terminate the conflict and midwife a settlement. Intervention could involve aiding one side to defeat another, or simply intervening militarily to choose the winner and the loser. Outsiders are often motivated to intervene because one side is seen to be committing more human rights violations than another, and that side becomes the chosen target. The important thing to note about this kind of thinking is that it assumes that outsiders could agree on a strategy, and could bring to bear overwhelming power if they chose to do so. It also assumes that once outside powers targeted their villains, they could simply isolate them from significant outside support. The military involvement of the powerful United States would ensure that the costs of the intervention would remain low, and thus induce other states to join a coalition.

After prevention and termination, the search for a stable settlement is the third phase of outside intervention in civil wars. Civil wars have a tendency to recur, and there is a risk that an ostensible settlement is really only a kind of break for rest and recuperation. The combatants retreat to their corners, and perhaps each hopes for the best; but insofar as they have been living in a Hobbesian state of nature for the duration of the fighting, each assumes the worst of the other. They arm against the possibility of the others' defection, they view any evidence of preparation for defection in the worst possible light, and they are tempted to engage in a preemptive or preventive return to war. Practitioners and scholars alike have concluded that outside interveners might be able to sustain peace agreements by acting as an enforcer of the peace agreement and the protector of any party victimized by another's cheating. The term “peace enforcement” was added to the term “peacekeeping” to capture this more muscular form of external assistance. The peace enforcers would need to be more capable and more willing to fight than traditional un peacekeepers. It helps if they are also significantly more capable militarily than any of the combatants in the war. There are only a few militaries in the world large enough, competent enough, and with the strategic reach to do this kind of work, especially following wars in which the combatants themselves have developed some real capability.9

The experience of the Balkan Wars in the 1990s provided both the object lesson of failure to engage in preventive diplomacy, and the template for intervention and peace enforcement. Outsiders did little to forestall the dissolution of Yugoslavia, and let the Slovenian and Croatian armed rebellions and secessions proceed without much diplomacy to prevent them. Secretary of State James Baker famously averred that the United States did not have a “dog in this fight.” Bosnia similarly disintegrated, and after years of bloody warfare, the United States and several allies helped to build up the Bosnian and Croatian forces against the Serbs, and then contributed nato airpower as these revived forces went on the offensive. Though Russia supported Serbia diplomatically, it had few cards to play at the time, and thus the central obstacle to Western direct intervention was the inability of Western countries to decide on an appropriate objective. The Europeans would have been content to partition Bosnia; the Clinton administration was not. It took additional years of bloody warfare, covert U.S. assistance to the Bosniaks and Croats, and the emerging possibility of a large prestige loss to nato to produce agreement among outsiders about a political objective. At the same time, the Bosniaks and Croats were subjected to some outside discipline during the final battles of the war, and were told by the United States that the complete defeat of the Serbs would also not be tolerated. As part of the Dayton Accords, nearly sixty thousand Western peacekeeping forces and political administrators were committed to Bosnia, with another twenty thousand nearby in support, to police a settlement that gave each of the three sides some of what it had fought for, but left all somewhat unsatisfied. Though admirers of the peace settlement observe correctly that the killing stopped and has not resumed, the Bosnia-Herzegovina thus created is politically unstable. De facto partition, proximity to Europe and its power, the eu's constant supervision, and Bosnian dependence on Europe for a livelihood keep the country together, but only in name.10

Kosovo did see an effort at preventive diplomacy, but the political solution recommended in the Rambouillet Accord amounted to the Serbian surrender of Kosovo to nato. Though a bit of a surprise to nato, the Serbs tested nato's seriousness in battle, and by all accounts the war was a surprisingly close thing. A un resolution provided a face-saving exit for Serbian troops from Kosovo, after which nato installed the peace-enforcement operation kfor (Kosovo Force) to assure that Serbian forces would not return, a mission that continues with some 4,500 troops today. Kosovo has since formally seceded from Serbia, though many countries do not recognize its independence. Responding to the arrival of nato's troops in Kosovo, a small unit of Russian troops in Bosnia raced for the Pristina airport to protect what the Russians perceived as their equities in the conflict. This could have precipitated a major crisis, but the kfor commander on the ground, British Army Lieutenant General Michael Jackson, chose to avoid a confrontation. The episode was a harbinger of how the intervention problem is likely to change as more great powers emerge and begin to see the course, management, and outcome of civil wars as matters of national interest.

For several reasons, early intervention to forestall outright civil war is less likely to occur in a world with more than one consequential power. First, simply because more traditional security challenges exist, even those liberal powers most prone to intervene have more to worry about from a security standpoint than they did in the “unipolar moment.” Potential civil wars will receive even less attention. Second, when a state becomes politically unstable, other consequential powers are likely to look at that instability through their own power and security interests. If one of them wishes to organize preventive diplomacy, others may ask how the outcome might affect their power and security. Third, because of these concerns, it will likely be more difficult to get the issue in front of the un Security Council and produce a resolution authorizing legitimate preventive diplomacy. Finally, as we have seen, new consequential powers do not wish to legitimate certain kinds of intervention. As Chuck Call and Susanna Campbell observe in the forthcoming companion to this volume: “Many states are therefore extremely focused on avoiding any transgression against the principle of state sovereignty that might set a precedent for intervention (including against their own government).”11 If an intervention is couched in terms of the responsibility to protect, these states are likely to mobilize the traditional sovereignty norm as a counterargument.

The coexistence of several consequential powers should also influence the course of civil wars. If the notion of a “hurting stalemate” has any traction as a potential source of settlements, then competitive outside interventions may make this less likely. Not all political instability that erupts into actual warfare will attract the interest of major powers, but some will. Though hardly dispositive, the number of civil wars that feature direct outside intervention has grown noticeably over the last decade.12 Outside powers could have a range of motivations attracting them to support one side or the other in a civil war. These include the possibility of actual gain of an ally or base in the event that their side wins, the cultivation of a “proxy” who might serve their interests at a later date, the domestic or international reputation that may emerge from demonstrating one's ability to influence such conflicts, or the desire simply to stymie the perceived interests of those outside powers that support the other side. Though the number of such cases cannot be predicted, it is likely that there will be some civil wars in which all the combatants attract outside backing, and thus they can call upon a steady stream of financial and military assistance. Civil wars that measure the power and will of the combatants must now measure the power and will of their external supporters. And the longer the wars go on, the more the citizens of the societies hosting the conflicts will suffer, and therefore the greater the number of internally displaced persons and refugees. These refugee populations are often seen as a security problem, which may motivate some of the neighbors to advocate more intensively for a settlement, but given the complexity of negotiating such a settlement with insiders and outsiders simultaneously, refugee-receiving countries may themselves be tempted to pick a side in the war.13

Finally, a changed structure of power should affect the nature of any achieved settlement, though the implications are a bit less clear. If one legacy of a war supported by consequential powers is that the combatants have become more capable than they would have otherwise, then settlements will require a visiting “leviathan” to police them. In other words, to keep such combatants safely in their respective corners, the peace-enforcement force will need to be quite capable itself. Those outside powers who supported one side or the other in the civil war probably possess the best forces for such a mission, but by virtue of their partisanship, they would not be trusted. Hence the peace-enforcement force may lack the capability to enforce against plausible spoilers. On the other hand, there may be a selection effect that cuts the other way. Any civil war with outside intervention that does achieve a negotiated peace will do so because the outsiders have agreed to it. Thus, the outsiders may have the greatest influence on their respective sides keeping to the peace agreement.

The Syrian Civil War, which began in 2011, has proven long, bloody, and immensely destructive. Disputes among the great powers stymied international preventive diplomacy, while direct and indirect military intervention by great and middle powers increased the strength of all sides, contributing to their ability and will to sustain the war. By 2016, there were at least four sides fighting within Syria, and at least five external states or clusters of states that had intervened on one or more sides.14 The war has many unique properties, and it would be wrong to attribute its terrible trajectory solely to the emergence of multipolarity.

Resurgent Russia made it difficult to coordinate international action to stabilize Syria. By spring 2013, Moscow had “issued three un Security Council vetoes, bent over backwards to water down the Geneva Communique calling for a peaceful transition of authority, and fastidiously avoided joining the call for ‘Assad to go.’”15 Close observers suggest that Russia has many overlapping interests in Syria, an important one of which seems to be normative. Russia opposes regime change, including regime change under the rubric of humanitarian intervention or r2p, partly because of the risk that this could ultimately legitimate an international effort to bring about regime change in Russia.16 China seems to share Russia's view, and also cast a veto in the un Security Council in October 2011.17 Brazil, India, and South Africa all abstained from supporting the resolution because they, too, oppose outside intervention in internal political disputes.18

In this arena for normative contestation, Russia and China have both exploited the legitimacy of the Security Council to stifle the effort to develop a new intervention norm. In contrast to its role in the Balkans, in which the United States and its Western allies bypassed the Security Council and attempted to assert that the victorious Cold War liberal coalition could legitimate its own wars, the United States has seemed less willing to go around the Council in the Syrian context. This may be because in a multipolar world, it is more important to the United States to protect the integrity of the sole institution in which great powers cooperate as equals; or it may be, as some have suggested, that Barack Obama was simply personally disinclined to go around the Council.

From the outset, the Syrian Civil War saw a pattern of external intervention in which bids for quick victory, in many cases enabled by outside aid, precipitated more outside intervention to stalemate initially successful offensives. These external interventions were often motivated by outsider interests in regional strategic objectives.19 Rather than producing either a victory or a hurting stalemate, competitive interventions produced a dynamic military competition, in which the competitors could always believe that with a bit more outside help, they might prevail. In contrast to the Bosnia endgame, in which the United States built up the Bosniak forces and then orchestrated a hurting stalemate to bring all to the table, no diplomatically useful balance of military forces has yet emerged in Syria. In Bosnia, almost all outside interveners worked in favor of the Croats or the Bosniaks; the Serbs could slowly be strangled. This is clearly not the case in Syria.

Precipitated by political activity across the Middle East associated with the “Arab Spring,” regime opponents in Syria launched protests and demonstrations starting in March 2011. Regime repression was often violent, but the regime also attempted to deal with the demonstrations politically, both with messaging and modest reforms. By May, however, the interactions between demonstrators and security forces became increasingly violent. The United States and Europe imposed a range of economic sanctions on Syria in response to the regime's behavior, but Russia and China vetoed the un Security Council resolution calling for an end to the regime's crackdown. During these early months of the struggle, regime opponents themselves turned increasingly to violence. The history of external intervention in this period has not been written, but by the last quarter of 2011, the “rebels” appeared well-armed and well-funded.20 Observers focus on the rebels' many weaknesses relative to the regime, which are real. But we should also note the rapid escalation of the fighting. Once the rebels began to have success against the regime, the regime found support abroad from both Iran and Russia. Iran seems to have committed itself to the regime in January of 2012.21 This precipitated still more outside assistance to the rebels, which prompted still more assistance to the regime. Theorists have observed this pattern in other wars, finding that it generally contributes to duration and destruction.22

Finally, the complexity of the battle map, featuring multiple international actors, seems to be affecting Western notions of a settlement. As previously noted, the Syrian Civil War consists of four major internal players. From a simple conflict between regime and rebels, the map is now characterized by a multiplicity of rebel groups, many of which are at war with each other. The “Islamic State,” in fact, formed when one rebel faction split from the others and aligned with like-minded Iraqis. Of the remaining rebel groups, the other offshoots of Al Qaeda seem to be the strongest, though they do not control the larger coalition, which is loosely organized at best. The Kurds have emerged as a faction in their own right, aligning themselves with the United States to fight the Islamic State, but, to the extent possible, staying out of fights with other groups while they try to carve out an autonomous zone. Given the military power of all these groups, outside interveners would have a difficult peacekeeping task ahead of them, even if those who had backed different sides could agree on a settlement. Increasingly, one hears of proposals based on de facto partition of the country.23 In the early phases of the war in Bosnia, the United States in particular would not support such an outcome, though the Dayton Accords ultimately produced a nominally unitary state that left the principal combatants in control of their own regions. Even this agreement required enormous policing in its first years. In Syria, it appears that observers now have even smaller ambitions: stabilizing group borders along the existing battle lines, with the exception of the Islamic State, which insiders and outsiders seem to agree must be annihilated.

Recent and plausible future changes in the global distribution of power demand analysis of their potential impact. Here I have probed how a shift from a unipolar to a multipolar world might affect the problem of international cooperation to prevent, terminate, and settle civil wars. This was mainly a deductive enterprise, supplemented with examples from two cases: the Balkan Wars of the early 1990s and the Syrian Civil War. Cases selected for their strong exemplary utility cannot prove an argument. The analysis is, however, suggestive. Preventive diplomacy will likely be fraught with competitive behavior among the strong powers possessing the capacity to suppress an escalating civil conflict; and this same competitive behavior will likely add military and diplomatic resources to the competing civil war factions, allowing them all to believe that another round of fighting and external assistance will bring victory. Finally, the Darwinian process of extended warfare may so increase the combat power of the parties that any negotiated settlement will require very capable peace-enforcement/peacekeeping forces to separate the combatants long enough for political and economic reconstruction to take hold. These problems will not characterize every civil war, because multipolarity also means that consequential powers are often busy with their own particular security problems. But they will be more prevalent than they were during the short lived “unipolar moment.”

If this analysis is correct, it provides a bit of advice for those statespersons who wish to take up the cause of the international management of civil wars. Diplomats may find it useful to be more circumspect in their purposes. Rather than assuming agreement, or the potential for agreement, among ideologically like-minded great powers, diplomats may need to return to a more traditional approach of finding elements of agreement among powers who largely see themselves in a competitive relationship. Post–Cold War approaches to civil war management tended to combine humanitarian and ideological (usually liberal) purposes. People needed help, but it was often believed that short-term help had to be combined with major political reform to ensure against future violence. Finding agreement on both sets of issues is difficult in any case, but will be much harder as more capable powers see more security interests at stake in these conflicts. The diplomacy of civil war management is no easier than any other kind of diplomacy, and cannot be reduced to a formula. But perhaps if outsiders reach for less, they will get more.


James D. Fearon, “Civil War & the Current International System, “Dædalus 146 (4) (Fall 2017); and Chuck Call and Susanna Campbell, “Is Prevention the Answer?” Dædalus 147 (1) (Winter 2018).


Henry Kissinger, World Order (New York: Penguin, 2014), 23–31; and Hendrik Spruyt, “Civil Wars as Challenges to the Modern International System,” Dædalus 146 (4) (Fall 2017).


For the seminal discussion of the bipolar influence, see Kenneth N. Waltz, “Structural Causes and Military Effects,” in Theory of International Politics (Boston: McGraw Hill, 1979), 161–193; and Kenneth N. Waltz, “The Stability of a Bipolar World,” Dædalus 93 (3) (Summer 1964): 881–909.


See the graphs under “Aggregate Power of Developing States Set to Surpass U.S. Power by 2030,” in National Intelligence Council, Global Trends 2030: Alternative Worlds (Washington, D.C.: Office of the Director of National Intelligence, December 2012), 16. Challenging the notion that unipolarity is waning is Stephen G. Brooks and William C. Wohlforth, “The Rise and Fall of the Great Powers in the Twenty-First Century: China's Rise and the Fate of America's Global Position,” International Security 40 (3) (Winter 2015/2016): 7–53.


Noel Anderson, Competitive Intervention and Its Consequences for Civil Wars (Ph.D. diss., Massachusetts Institute of Technology, September 2016) argues that the bipolar competition incentivized great-power intervention in civil wars, but fear of escalation to war between great powers at the same time made the superpowers chary of helping their clients achieve complete success, thus tending to lengthen civil wars. Anderson demonstrates this dynamic mainly during the Cold War, with reference to the bipolar U.S.-Soviet competition.


National Intelligence Council, Global Trends 2030, 15–20; and National Intelligence Council, Global Trends: Paradox of Progress (Washington, D.C.: Office of the Director of National Intelligence, 2017), 25–28.


On the political barriers to preventive action within states and multilateral organizations, see Call and Campbell, “Is Prevention the Answer?”


Fearon notes that the average duration of civil wars has been going up, but those wars that do end are more likely to end with victory by one side than by negotiated settlements. See Fearon, “Civil War & the Current International System,” Figure 3, “Accumulation of Long-Running Conflicts, 1945–2014.” This tells us that civil wars are hard to end under any circumstances, but military success is often the key. In his essay in the forthcoming Winter 2018 issue of Dædalus, Sumit Ganguly notes that the twenty-five-year-long Sri Lankan civil war was brought to an end only with an extremely brutal offensive, after the Tamil Tigers were entirely isolated internationally and the regime received significant assistance from China and Pakistan. Sumit Ganguly, “Ending the Sri Lankan Civil War,” Dædalus 147 (1) (Winter 2018).


Jean-Marie Guéhenno, “The United Nations & Civil Wars,” Dædalus 147 (1) (Winter 2018) observes that local combatants have become sufficiently strong that even un peacekeeping operations require “a much greater engagement from the best-equipped armies of the world, which must provide the un with the mobility, firepower, and intelligence that will allow un peacekeepers to act early and decisively.”


Tanja A. Börzel and Sonja Grimm discuss the eu missions in Bosnia and Kosovo in “Building Good (Enough) Governance in Postconflict Societies & Areas of Limited Statehood: The European Union & the Western Balkans,” Dædalus 147 (1) (Winter 2018). Their assessment tracks roughly with mine.


Call and Campbell, “Is Prevention the Answer?”


Internationalized armed conflicts are “conflicts in which one or more states contributed troops to one or both warring sides.” Therése Pettersson and Peter Wallensteen, “Armed Conflicts, 1946–2014,” Journal of Peace Research 52 (4) (2015): 536. See also Nancy Lindborg and Joseph Hewitt, “In Defense of Ambition: Building Peaceful & Inclusive Societies in a World on Fire,” Dædalus 147 (1) (Winter 2018), in which the authors suggest: “Today internationalized internal conflicts account for one-third of all global conflicts, have contributed to the 500 percent increase in global battle deaths over the past ten years, and have pushed conflict deaths to a twenty-five-year high.” These data understate the problem, because they omit strictly indirect foreign intervention in the form of money and weaponry.


In her contribution to this volume, Sarah Lischer reviews why refugee-receiving states often perceive their guests as security problems, and how these concerns may contribute to the regional spread of conflict. Sarah Kenyon Lischer, “The Global Refugee Crisis: Regional Destabilization & Humanitarian Protection,” Dædalus 146 (4) (Fall 2017).


Max Fisher, “Straightforward Answers to Basic Questions about Syria's War,” The New York Times, September 18, 2016,


Samuel Charap, “Russia, Syria and the Doctrine of Intervention,” Survival 55 (1) (2013): 35–41, esp. 36.


Ibid. See also Roy Allison, “Russia and Syria: Explaining Alignment with a Regime in Crisis,” International Affairs 89 (4) (2013): 795–823, which reviews the range of reasons that Russia has supported the Syrian regime and suggests that an unwillingness to legitimate un action to change regimes is one of the most important (817–820).


Allison, “Russia and Syria,” 799–800.


Howard La Franchi, “Syria Vote May Prove Costly for Three Countries Seeking More un Clout,” Christian Science Monitor, October 5, 2011.


For a review of the interests and actions of the principal regional powers, especially Saudi Arabia, Iran, Qatar, and, to a lesser extent, Turkey, see Emile Hokayem, “Iran, the Gulf States and the Syrian Civil War,” Survival 56 (6) (2014): 59–86. Dating Turkey's intervention to fall 2011, see Aaron Stein, “Turkey's Evolving Syria Strategy,” Foreign Affairs, On Turkey's motivation to expand its regional influence, see International Institute for Strategic Studies, “Turkey's Diminishing Policy Options in Syria,” Strategic Comments 22 (7) (2016).


Roula Khalaf and Abigail Fielding-Smith date arms deliveries from Qatar through Turkey beginning in “early 2012,” which, by mid-2013, may have been worth $3 billion. Roula Khalaf and Abigail Fielding-Smith, “How Qatar Seized Control of the Syrian Revolution,” Financial Times, May 17, 2013, See also “German Magazine says Libya Arms, Funds, Trains Syrian Rebels,” Focus, December 5, 2011, accessed through bbc Monitoring Europe, December 6, 2011; and “Lebanon: Arms Smugglers Thrive on Syrian Uprising,” The Daily Star, November 25, 2011, accessed through bbc Monitoring, November 26, 2011.


Hokayem, “Iran, the Gulf States and the Syrian Civil War,” 73–75.


Max Fisher, “Syria's Paradox: Why the War Only Ever Seems to Get Worse,” The New York Times, August 26, 2016,


David Iaconangelo, “Would Decentralizing Syria Offer a Path to Peace?” Christian Science Monitor, September 17, 2016.

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