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date: 19 September 2017

State and Nonstate Armed Groups (NAGs) in International Relations Theory

Summary and Keywords

The international arena has been plagued with violence committed by a variety of Nonstate Armed Groups (NAGs), including ethnic and religious insurgents, terrorists, and revolutionaries, which threaten not only the states they target but also the entire world’s stability and security. An intriguing observation related to armed groups is their ability to attract outside state supporters. Indeed, almost half of all groups that emerged in the post-World War II period received some form of backing from states including but not limited to funds, arms, and safe havens. In this respect, it is possible to draw parallels between interstate alliances and state–group alliances. The major International Relations theories—realism, liberalism, and constructivism—have significant insights to offer in explaining the origin and evolution of state–rebel group alliances. These insights are empirically tested using new data on outside state support of rebel groups that emerged in the post–1945 period. Two forms of alliances exist between states and groups: strategic or instrumental and principled or ideational. A strategic alliance occurs if a state supports a group fighting against its enemy or rival, so security-related concerns and common threat motivate a given alliance. An ideational or principled alliance occurs if a state supports an ideationally contiguous armed group with which it has ethnic, religious, and/or ideological ties. Whether there is a strategic or principled alliance between armed groups and their state supporters has implications for the onset, course and termination of non-state violence in world politics.

The empirical findings using large-N statistical analysis show that (1) states form alliances with rebel groups in both the absence and presence of interstate hostilities; (2) states form alliances with ideationally contiguous rebel groups, that is, groups that have common ethnic, religious, and ideological ties to states’ population and/or a group of people in its society; (3) democratic states do not ally with rebels, which fight against other democratic states; and (4) states, in general, are less likely to support rebels, which fight against ideationally contiguous states. Socialism emerges as a unifying ideology contributing to a high degree of solidarity both among states and between states and armed groups. The empirical findings imply that the perceived motivation of state supporters by armed groups; whether states support rebels due to strategic or ideational concerns, should have some influence on armed groups’ level of lethality, duration, and attitude toward civilians and governments they fight against. Only a fully developed research agenda offering empirically informed theoretical insights can address these questions by facilitating future venues of research on the origin and evolution of state–NAG alliances.

Keywords: alliance, state support of rebels, empirical international relations theory, terrorism, sovereignty, civil war and its transnational dimensions


The modern state system is under an unprecedented attack by nonstate armed groups, which primarily use violent means to pursue certain political and territorial objectives. In the domestic realm, nonstate armed groups (NAGs) have come to challenge states at multiple fronts, claiming territorial autonomy, secession and/or political reforms. Internationally, the actions of NAGs transcend the borders of multiple states through the mechanism of either outside intervention or spread of conflict into the borders of neighboring states. Therefore, internal conflicts are frequently transformed into interstate conflicts, as can be witnessed in the ongoing case of Syria. More surprisingly, though, states have come to rely more often on armed groups to tackle both internal and external political challenges.

Out of 454 armed groups that emerged in the post–1945 period, almost 50% were intentionally backed by states (San-Akca, 2015, 2016). A total of 111 states ended up providing some form of support to armed groups for some time in the years between 1946 and 2010. The most notorious cases of state-armed group collaboration, such as Iran’s backing of Hezbollah and Syria’s support of Hamas, look similar to interstate alliances in terms of the level of commitment each side has made toward one another and the duration of their collaboration. Although there is extensive research on the emergence and evolution of interstate alliances, research on state–NAGs alliances in the field of international relations is nonexistent. The most recent research trying to study these alternative forms of alliances emerged in the context of studies examining the transnational dimensions of civil war or outside intervention in civil war. This body of research has developed in an interdisciplinary fashion by building on theories from multiple disciplines of Social Sciences, such as Political Science and Sociology, which explain onset, evolution, and spread of civil war and domestic political contention.


In a visit to Turkey in January 2016, then-Vice President Joe Biden declared that PKK (the Kurdistan Workers’ Party) was doing harm to Turkish citizens and was a “terrorist group.” In addition, he stated that there was no difference between PKK, ISIS (the Islamic State of Iraq and Syria), and al-Nusra. He reiterated the long-held U.S. view that Turkey was a strategic ally of the United States and that the cooperation between Turkey and the United States in fighting against terrorism would continue.1 At the same time, Biden and other U.S. government representatives made it clear that they did not have the same perception about the PYD (Democratic Union Party) and the YPG (People’s Defense Units), two Kurdish rebel groups fighting against the Assad regime in Syria. Indeed, they stated that the United States supported the PYD and YPG because they were fighting against ISIS. During his visit, Biden also stated that there were joint plans with Turkey to bolster the Sunni rebel groups, in general, fighting against the Assad regime in Syria. At a press conference on October 2, 2015, President Obama mentioned the disagreement with Russia about the Sunni rebel groups fighting to topple the Assad regime. Russia’s indiscriminate attitude toward ISIS and other regime opposition forces in Syria had been obvious since the beginning of Russian air strikes in Syria on September 30, 2015. From the perspective of Russia, ISIS and other Sunni opposition groups were all terrorist organizations, which were fighting against the legitimate government in Syria (Rushing, 2015).

These examples illustrate the complex and fluid web of relations between armed groups and states in general. Why do states perceive some rebels as friendly and others as unfriendly? What does an analysis of interstate relations offer when it comes to developing a systematic explanation for some rebel groups receiving support from states whereas some others do not receive any backing?

Given the frequency and depth of cooperation between states and rebel groups, it is surprising that International Relations scholarship has mostly studied it on the outskirts of the field. More specifically, such cooperation is assumed to emerge only to the extent that states are willing to benefit from rebel groups as agents of proxy wars. Yet, proxy war is a limited conceptualization of these complex interactions. It is biased against nonstate actors, implying that they exist to the extent that states need them as proxies. The purpose of the present text is not to claim that they are equal to states with respect to two main criteria of statehood: international recognition and domestic legitimacy. Rather, it is to explain the conditions under which states accept them as partners and opt supporting them as a policy tool. In order to offer a systematic analysis of the emergence of state–NAG alliance ties, the following questions are addressed:

  1. 1. What does International Relations theory offer about this alternative form of partnership and alliance? Is it irrelevant? Is there room for state–NAG alliances in the analysis of international relations?

  2. 2. What does the empirical research thus far reveal about the emergence and evolution of these alliances? Why should anyone care about state–NAG alliances?

  3. 3. What do empirical findings yield about the consequences of state–NAG alliances for interstate conflict and cooperation?

Based on the conventional theories of international relations, hypotheses about the origin of state–NAG alliances in world politics are presented and tested. An alliance exists between a state and a rebel group when the state ends up providing any of the following forms of support for the group in question: safe havens, training, weapons and logistics aid, training camps, troops, and funds. Following the lead of major theoretical approaches to the study of international relations, it is argued that there are two major types of state–NAG alliances: strategic or instrumental and ideational or principled alliances. Strategic alliances refer to cases in which the target state of a rebel group poses a security threat to the supporter state; that is, targets and supporters are rivals or have a history of hostilities. Ideational or principled alliances refer to cases in which states support rebel groups since they have common ideational ties with them. These ideational ties include ethnic, religious, and/or ideological ties.

External state support of rebel groups has received much scholarly attention in the past two decades (Byman et al., 2001; Salehyan, 2007; Salehyan, Gleditsch, & Cunningham, 2011; San-Akca, 2009; Bapat, 2012). Yet, this existing body of work either specifies the theoretical insights without testing them empirically or cannot go into detailed empirical tests since the existing data on external support does not allow for further testing (Salehyan, 2010; Salehyan et al., 2011). Such limitations impede further development of theory and refinement of explanations about the origin and evolution of state–rebel group interactions. Even though a significant body of knowledge has accumulated about the role of state support for rebels in the internationalization of internal conflict in general, this body of research focuses on the consequences of state–rebel alliances rather than on their origin and evolution. Considering that we reached an advanced stage of military technology, where nuclear weapons render direct war among states very costly, it is more likely to see states collaborating with rebel groups to reach their objectives abroad more frequently in the future.

The purpose here is not to downplay the existing research, but rather to help develop a new research agenda by appealing for scholarly attention, specifically mainstream scholarship, to the role rebel groups play in world politics and to the fact that states frequently partner with them. Therefore, as is reflected here, the focus of existing research is shifting from the consequences of state–rebel cooperation for interstate relations to study of the origin and evolution of their cooperation. The goal is to pave the way for future research on how these alternative forms of alliances influence the strategy of rebel groups and states, as well as how they are shaped by the nature of the interstate system and relations. Such research also has implications for the future of state-making in world politics.

The international environment contains some signals for NAGs, both before and after they start engaging with their target governments (Jackson et al., 2017). It matters if they receive signals for the presence of strategic or principled support from outside states. Indeed, whether they anticipate strategic or ideational support from some states should influence the instruments they use, that is, violent versus nonviolent, the way they treat their support base within the society, as well as how they respond to their target governments (whether or not to negotiate). On the one hand, if they try to appeal to democratic states, for instance, to get their backing, they might be more cautious in avoiding indiscriminate violence against civilians. On the other hand, if they try to appeal to the rival states and enemies of their targets, they might engage in a high level of violence to prove that they are determined and deserve to be considered as potential allies against the common enemy. In order to develop systematic evaluations of these insights, the existing research on external state support for NAGs has to go beyond identifying empirical regularities about the patterns observed in some large-N dataset on outside intervention in internal conflict or external support of rebel groups. State and NAGs alliances deserve a place in the mainstream research about international relations.

External Support, Internal Conflict, and International Relations Theory

It has been almost three decades since Stephen Walt stated that “how states choose alliance partners will shape the evolution of the international system as a whole” and “failure to understand the origins of alliances can be fatal” (Walt, 1987, pp. 1–2). Walt focuses on interstate alliances, since in his view of the world and the school of thought he represents—realism—there is little room for nonstate actors. As stated previously, the study of armed conflict most recently embraces an approach that disaggregates actors involved in internal conflict and acknowledges transitivity between interstate and intrastate conflicts. Nonstate armed actors are recognized as influential actors in world politics. This development is timely, given that most armed conflicts in the world occur within the borders of states and most interstate conflicts seem to be a result of external intervention in internal conflicts.

Conflict studies seem to develop as a separate field, dismissing almost all accumulated knowledge about how international relations work according to the major paradigms developed in the past half century. Whenever states support armed rebel groups, their behavior is reduced to be analyzed as a transnational dimension or externality of civil war. This is so because scholars in the field of International Relations pay little attention to state–rebel group interactions as one of the main forms of relations in the international arena. Therefore, the study of these interactions is conducted through the lens of either the internalities or externalities of civil war, as if states interact with rebel groups only during civil wars. Several examples, such as Iran’s support of Hezbollah and Syria’s support of the Palestinian Islamic Jihad (PIJ), emerged prior to the onset of violence by these groups and continued long after conflict termination. In other words, outside states deliberately contribute to the formation and endurance of certain groups, thus causing civil war in a given state, rather than waiting to act after the onset of conflict.

Furthermore, although internal conflict has been studied within various research fields, such as ethnic conflict, civil war, terrorism, intervention, and mediation, support for nonstate armed groups as a foreign policy strategy has hardly been the subject matter of the main core Comparative Politics or International Relations research fields. Nevertheless, it is important to identify the existing lines of research examining the interactions between states and rebel groups in order to drive home their analysis, which could benefit from the accumulated knowledge in the study of alliances between states. The demise of communism and the Soviet Union at the beginning of the 1990s marks the departure of conflict studies from a focus on power rivalry among peers as the major research question in the study of international politics. The rise of nonstate violence in the post–Cold War period, especially in ex-communist multiethnic states, such as Yugoslavia and the Soviet Union, has directed scholarly attention to the mechanisms related to the onset and transnational causes and effects of ethnic conflict.

The conventional wisdom, at the time, suggested that the termination of superpower rivalry would make insurgency and rebellion difficult since rebels would not be able to find resources readily available at their doorsteps anymore. Rather, they would have to take the initiative to secure resources through alternative channels, such as diaspora support (Kalyvas & Laia, 2010). Indeed, the rebels managed to acquire resources through such channels, no longer relying on direct state sponsorship (San-Akca, 2016). Exploring the ways ethnic and religious rebels secure external resources and their effect on ethnic conflict and civil war onset produced valuable research (Saideman & Jenne, 1992; Carment, 1993; Carment & James, 1996, 2000; Saideman, 2001, 2002; Cederman, Girardin, & Gleditsch, 2009). We now know that ethnic kin, diaspora, and domestic political considerations help ethnic insurgents and rebels acquire the human and material resources they need to carry on their violent campaigns against their target states.

More systematic analysis of rebels’ access to external support has developed under two bodies of research since the 1990s. One is the study of outside intervention in internal conflict, which examines the conditions under which outside states intervene in the internal conflicts of other states (Regan, 1996, 1998, 2000; Aydin & Regan, 2011; Aydin, 2012). The second body of research disaggregates the parties to conflict in civil wars and explores the conditions under which outside states support rebel groups and the implication of such support for conflict outcome and interstate relations in general; i.e., the relations between targets and supporters of rebels. This recent body of research finds that (1) states see the rise of rebel groups targeting their rivals or adversaries as an opportunity to fight their enemies covertly (San-Akca, 2009; Maoz & Akca, 2012); (2) states are motivated by ideational concerns, as much as security concerns; (3) rebels also select the states from which they seek support (San-Akca, 2016); (4) outside intervention influences the duration of civil wars (Cunningham et al., 2009; Cunningham, 2010); and (5) supporting rebels leads to interstate conflict (Gleditsch, 2007; Gleditsch, Salehyan, & Schultz, 2008; Salehyan, 2008a, 2008b).

Although this recent body of work contributed significantly to an understanding of the transnational consequences of civil war and the implications of outside states’ siding with either of conflicting parties for the course and termination of civil wars, little is known about the transnational causes of states’ alignments with rebel groups. Furthermore, new research started examining intergroup alliances to elaborate the motives of rebels in allying with other rebel groups in a civil war. Although this research is still in its infancy, the recent analysis of civil wars based on large-N datasets has shown that rebels are driven by strategic, rather than ideational, motives in seeking alliance with other rebels (Christia, 2012). This finding is also in line with research, which emphasizes strategic interest as the major source of interstate alliances (Walt, 1987).

Whether the major historical paradigms of International Relations, i.e., realism, liberalism and constructivism, is still relevant for the broader study of interstate relations is not discussed in detail here since it would require a separate paper. Yet it is possible to show how International Relations theory could still be relevant for examining the ties states develop with rebels. Such a theoretical engagement is necessary to develop an autonomous research agenda on these ties. This research agenda should not be guided by the empirical regularities discovered from analysis of large datasets, but rather by theoretical insights that could potentially be driven from research on states’ behavior in the international arena. Of course, one cannot deny the role of empirical regularities in refining theoretical insights, but that is the case only if the research itself is driven by initial theory. The scholarship should reach at an optimal meeting point between developing new theoretical insights and exploring empirical regularities. Otherwise, the new actors and challenges faced in the international arena will lead to dissolution of International Relations discipline.2

To survive as a discipline, International Relations needs to continue accumulating theoretical and empirical knowledge driven by a coherent research agenda, with an objective to develop parsimonious explanations about the ways states interact in the shadow of these newly emerging actors and challenges. This knowledge should also address questions about how systemic, domestic, and individual-level factors shape and are shaped by interstate interactions. Therefore, accommodating these new actors is required both theoretically and empirically. The goal here is to show how existing theories, initially designed to explain state-to-state interactions, can be useful in understanding the origin and evolution of state-to-NAG relations. The present purpose is not to object to the formulation of new theories but to contribute to the formation of new theoretical insights by building on robust foundations, which are the result of decades-long scholarly research on inter-state relations.

Building on three main schools of thought in the study of international politics (realism, constructivism, and liberalism), systemic, domestic, and individual-level explanations are offered about the origin of state–NAG alliances in international politics. Figure 1 presents the possible cause-and-effect relationships between state–NAG alliances and international conflict and cooperation. The advancement in technology and the spread of liberalism in world politics make it difficult to wage wars directly for two reasons: (1) it is hard to determine the winning side in the end since technological advancements have increased almost every state’s capacity to hurt the other one; and (2) it is hard to justify war by politicians, who hold offices in liberal societies. It seems that the future of world politics will continue to include armed rebel groups as one of the major actors. Therefore, it is about time that systematic explanations be developed about the origins of states’ alliances with them, which will help explain not only the course, evolution and termination of rebels’ conflict with states, but also have implications for the newly emerging research on rebel governance (Mampilly, 2011).

State and Nonstate Armed Groups (NAGs) in International Relations TheoryClick to view larger

Figure 1. IR Theory and State-NAG Alliances

Realists see foreign policy as a product of the changes in the external environment of states (Waltz, 1959, 1979; Morgenthau, 1963).3 States make foreign policy choices by calculating the relative capabilities and motives of their rivals. In catching parity with their adversaries or rivals, it is conventionally assumed that states will strive to balance against them by forming external alliances with other states (Waltz, 1979; Walt, 1985, 1987)4 or by mobilizing internally through arms buildup (Jervis, 1989; Art, 2000). Indeed, most of Cold War period was characterized by superpower rivalry to acquire proxies in the borders of other states in order to expand one’s sphere of influence vis-à-vis the other. Therefore, from the perspective of realism, supporting rebels fighting against other states is easily interpreted as an act to expand one’s own power and influence against the others in the international system. The present situation in Syria offers an excellent example of such a rivalry between US and Russia especially if one thinks why US and Russia agree on supporting the same rebel group despite many other differences they have about the resolution of Syrian conflict, i.e., whether the Assad regime should remain. Both US and Russia have committed to support YPG/PYD in the fight against ISIS since they see it as an opportunity to expand their influence in the region. Failing to support YPG may end with one side acquiring more influence over the course of the ongoing conflict at the expense of the other. Therefore, neither Russia nor US is likely to abandon YPG at this point.

A further derivation from realist thinking is that states support NAGs to balance against their adversaries when they are unable or unwilling to achieve parity through conventional means, that is, external and/or internal balancing.5 States might prefer this option if they are constrained domestically to mobilize human and material resources and/or have difficulty allying with conventional state allies. Realism, as Waltz (1979) and Walt (1987) have identified it, assumes that the structure of the international system constrains the behavior of states. If the balancing is the dominant strategy, for Walt, states are more likely to balance against rising threats by joining the weaker side. In other words, the structure of the international system (e.g., unipolar, bipolar) provides hints to states about the alliance strategy they should pursue.

Parallels can be drawn between the behavior of states in seeking, forming, and accepting alliances with other states and in providing financial, military, and logistics provision to rebels. One of the reasons behind Turkey’s admission to NATO (North Atlantic Treaty Organization) was the US’ willingness to prevent Turkey from going under the influence of the Soviet Union during the Cold War period. In his study of the alliances in the Middle East, Barnett (1996) argues that the construction of a common “Arab national identity” helps to define common threats and explain alliance patterns. Walt (1987) agrees that ideology influences interstate alliances, but only to the extent that it is part of the threat environment posed by the actor against whom allies unite. In other words, ideology is part of the definition of the “other” and has no independent effect on state behavior other than the times that the “other” is perceived as a security threat. When the security of states is at stake, ideology does not motivate them to seek alliance with each other; rather, security concerns override the ideational motives of states in forming alliances.

Per the teachings of realism, the following hypotheses are drawn:

H1: States are more likely to support rebels, who fight against their adversaries than rebels that target nonadversaries.

H2: The likelihood of states’ support to ideationally contiguous rebel groups increases if they are relatively strong vis-à-vis rebels’ target states (since ideology is inferior to security concerns for motivating the formation of alliances).

H3: States are more likely to support rebel groups if there are other states supporting the same rebels.

H4: States are more likely to support rebels against their external enemies if they do not have conventional state allies.

Constructivism assumes mutual construction of the agent and structure (Kubalkova, Onuf, & Kowert, 1998; Hopf, 2002; Klotz & Lynch, 2007). The agent refers to the states in the international arena, and the structure refers to the international system in general. Ideational identity is considered to influence states’ perceptions of others’ motives and interests (Wendt, 1992; Jepperson, Wendt, & Katzenstein, 1996; Checkel, 1998). A foreign policy outcome is a function of a state’s perception of its international environment, which is shaped by its ideational characteristics. Based on this argument, one would expect states to support rebels with whom they share a common ideational identity, such as ethnic kinship, religious affinity, and worldview and/or belief system.

Although existing research provides some findings about the role of rebel group strength and ethnic ties, it does not explore the causal mechanisms that make states form strategic or ideational alliances with rebels (Salehyan et al., 2011). As mentioned previously, ethnic kin has long been proven to be significant for the ethnic rebels’ ability to find safe havens and resources within the borders of other states (Weiner, 1971; Carment, 1993; Van Evera, 1994; Carment & James, 2000; Saideman, 2001, 2002; Carment, James, & Taydas, 2009; Cederman et al., 2009; Cederman, Gleditsch, Salehyan, & Wucherpfennig, 2013). A broader set of ideational ties connect states and NAGs, going beyond ethnic ties. Religious ties and political ideology are equally significant components of states’ and rebels’ identity. The varieties of ideational ties have not received adequate scholarly attention in terms of their effect on state-armed group alliances.

Furthermore, constructivist scholars argue that norms, beliefs, and ideas, which are the components of ideational identity, have as much influence on states’ foreign policy behavior as strategic interest, although they do not agree on how and why norms, beliefs, and ideas matter (Goldstein & Keohane, 1993; Katzenstein, 1996; Checkel, 1998). The debate over interests versus ideational identity and how each defines the other has long occupied scholarly work.6 The purpose here is to adopt and test constructivist teaching that ideas influence and shape the foreign policy decisions of states (Finnemore, 1996; Katzenstein, 1996; Finnemore & Sikkink, 2001). The empirical analysis here is also timely, given that some newly emerging research examines rebel group splits and mergers and finds that rebels are driven by strategic interests rather than identity in forming alliances with other rebel groups (Christia, 2012). In other words, realism’s theoretical insights have now been applied and tested to the study of interstate and intergroup alliances. In both cases, strategic and material concerns seem to dominate the alliance decisions.

Ideational identity represents more than the ideological tendency of a government or a state. The identity of a state encompasses the broader ideational characteristics of its society, such as ethnolinguistic characteristics, religious beliefs, and worldview. Although the target of a NAG is not an adversary, the presence of ideational affinity with the group obligates a leadership to support it. This is in line with the findings of scholarly work on ethnic ties and their influence on states’ intervention in ethnic conflicts of other states, as mentioned previously (Saideman, 2001, 2002). It is possible to draw the following hypotheses by building on constructivism:

H5: States provide support to ideationally contiguous NAGs, even in the absence of external security concerns.

H6: States are more likely to support ideationally contiguous rebels when multiple groups are fighting the same enemy.

A further implication of ideational ties means that states also care about their ideational ties with other states. Indeed, the research agenda of democratic peace is driven by such an understanding of sharing common norms and domestic regime type. Both are reliable measures of state’s ideational makeup (Doyle, 1986; Lake, 1992; Maoz & Russett, 1993; Russett, 1996). The ideational affinity between a group’s target and supporter is also significant. States might avoid supporting rebels against ideationally contiguous states. Although Huntington’s clash of civilizations thesis does not seem to hold when it comes to explaining interstate conflict (Huntington, 1993a, 1993b; Henderson, 1997; Russett, Oneal, & Cox, 2000), it would be interesting to see if common civilization ties dissuade external support of rebels within a dyad in which two countries have a similar social makeup with respect to major ethnicity, religious identity, and ideological characteristics.

H7: States are less likely to support rebels fighting against ideationally contiguous states.

The liberalist school of thought also has significant theoretical insights to offer about the cooperation between states and rebels. Considering that the country with the highest capacity to wage direct wars happens to be also an advanced democracy, it is expected that leaders need to engage in lots of convincing to use force abroad. Therefore, NAGs are convenient partners for democratic leaders, who do not want to risk the lives of their citizens to their national interest abroad. Liberalism, in its broad sense, refers to a school of thought in the study of international relations that takes into consideration interstate trade volume, domestic institutions (such as regime type), and individual survival motives of leaders in explaining conflict and cooperation in interstate politics. In the present context, some insights from liberalism might offer an explanation related to domestic political survival motives of leaders. Applying the logic of democratic peace, one might argue that the likelihood of support declines if a dyad of target and supporter are both democracies (Maoz & Russett, 1993; Bueno de Mesquita, Morrow, Siverson, & Smith, 1999).

H8: Democracies are less likely to support rebel groups targeting other democracies.

On the other hand, democracies are also expected to support self-determination movements since the normative environment after the foundation of the United Nations gives way to secessionist movements, which claim statehood and state-making on the basis of distinct ethnic identity. The preceding theoretical insights imply that the nature of bilateral interstate relations favors either strategic/instrumental state–rebel alliances or principled/ideational alliances. Depending on these signals, it is possible to identify the role of anticipated external support in the likelihood of rebellion (Jackson, Maoz, & San-Akca, 2017). Furthermore, whether rebel groups expect provision from strategically or ideationally motivated outside states should influence the strategy they pursue in fighting against target governments. They might use discriminate violence towards civilians if they expect support from democratic states.

Three ideologies have been dominant with respect to social, political and economic life in the past century: nationalism, liberalism, and socialism. As a result, nonstate armed groups emerged to challenge states based on the ideology that suitably served their purpose. Most significantly, the adoption of any ideology has been a function of whether major states promoted it. For example, regardless of domestic regime type, states, especially major powers, have adhered to the principle of self-determination in the past century. Nationalism is used to motivate collective action as the main state-making instrument. Ethnonational NAGs picked these signals and emulated states in their claims for territorial autonomy or secession for a long time. At the systemic level, they got signals that favored an environment for building states on the notion of nationhood. At the regional or local level, depending on the prevalent ideology, most of these groups emerged as popular liberation movements for oppressed people. It is no surprise that during the Cold War period, the rhetoric of socialism was utilized extensively to appeal to the major power, which competed to expand its sphere of influence. The subsequent empirical analysis present original data and some descriptive statistics about the ideology adopted by rebels in the past few decades.

Research Design and Data

The empirical analysis is based on a triad-year as the unit of analysis given the nature of hypotheses being tested here. A triad consists of a rebel group, a target state against which rebel group fights, and a potential supporter, which is expected to turn into an actual supporter for the rebel group. There are three major sets of interactions within a triadic network: the one between potential supporter and rebel group; between target state and rebel group; and between target and potential supporter. To identify the potential supporter states for each rebel group, the politically relevant group (PRG) of a target state is identified. The PRG of a state includes geographically contiguous states, regional powers, and major powers. Each state in the PRG of a target state is listed as long as a rebel group’s activity continues. The assumption is that, unless conflict terminates, a potential supporter has the opportunity to support a given rebel group.

A new dataset is used to identify state and rebel group alliances. It has information on external state support for ethnic, religious, and revolutionary rebels. The NAGs dataset is used to capture the varieties of state–NAG alliances in the period between 1946 and 2010 (San-Akca, 2009, 2015, 2016). The dataset has information on 454 NAGs that existed in the post–World War II period.7 It is a triadic dataset including information on specific characteristics of NAGs and various forms of tangible support that states provide them. The NAGs dataset consists of cross-sectional time-series data, which allow for capturing changes in the behavior of states and NAGs over time.8 As mentioned earlier, at least half of these groups have managed to secure support from states in the form of safe havens, funds, weapons, and troops. Figure 2 shows the distribution of rebel groups with specific forms of support within the total number of rebels.

State and Nonstate Armed Groups (NAGs) in International Relations TheoryClick to view larger

Figure 2. Distribution of Rebel Groups with Outside State Support

Most frequently, rebels seem to get weapons and logistics, safe haven for their militants and leaders, and permission to operate offices within the borders of supporter states. Twenty-seven percent of all NAGs received weapons and logistics provision from outside states. Twenty-three percent of all groups managed to acquire safe havens for their leaders and operate offices within the borders of outside states. By the same token, 22% found safe havens for their militants in the borders of outside states. Figure 3 shows the distribution of years, with specific forms of support in the entire years of state support.

State and Nonstate Armed Groups (NAGs) in International Relations TheoryClick to view larger

Figure 3. Distribution of Support Types in Total Number of Support Observations

The highly persistent forms of support prove to be the provision of safe havens. Of the total number of observations of support, 59% include the cases in which states provide safe haven to rebel group militants and 55% include safe haven for leaders. Furthermore, 44% of total observations of support include provision of weapons and logistics aid, and 40% includes financial aid. These figures are correlated with the difficulty of terminating a specific type of support once it is provided. For instance, once a state opens its borders to rebel militants, it is very difficult to get rid of them.

Another similarly extensive dataset on state support of rebel groups is UCDP external support data (Högbladh, Pettersson, & Themnér, 2011). Although it is a dyadic dataset containing information on external state and nonstate supporters for rebel groups and governments involved in conflict and on various types of support, it is limited in terms of its temporal domain. It covers the period between 1975 and 2010. While the NAGs dataset contains approximately 16,000 observations, the UCDP external support dataset has around 6500 observations. Furthermore, the UCDP dataset contains 1940 observations for years in which the rebel side received support from outside states, whereas the NAGs dataset contains 4713 positive support observations. In addition, the NAGs dataset contains information on the ethnic, religious, and ideological characteristics of NAGs (left- vs. right-oriented) as well as whether they have a domestic support base and affiliated political party wings, which makes it possible to conduct more detailed empirical analysis. Figure 4 shows the distribution of NAGs according to these ideational characteristics. The highest proportion of support in each category of support type seems to be granted to ethnonationalist NAGs, followed by left-oriented, then democracy-oriented and religious-oriented NAGs.

State and Nonstate Armed Groups (NAGs) in International Relations TheoryClick to view larger

Figure 4. Distribution of Support Types by Group Identity

The empirical analysis evaluates the findings against the background of what we know so far from the existing empirical research on external state support for rebel groups.

  1. 1. States frequently support the enemies of their enemies when the opportunity rises. External threat perception and security seem to drive alliances between states and NAGs (Salehyan, 2010; Maoz & Akca, 2012; San-Akca, 2016).

  2. 2. Ethnic ties consistently drive outside intervention into internal conflicts. States intervene on the side of rebels if they share ethnic ties with them. There is extensive research on various types of ethnic ties and how they matter (Saideman & Jenne, 1992; Davis & Moore, 1997; Saideman, 1997; Cetinyan, 2002; Carment et al., 2009, Cederman et al., 2009, 2013; Checkel, 2013). If ethnic kin have access to political power and make up a major group in a society, it is less likely to support rebels in neighboring states, who are ethnic kin.

  3. 3. Weak state capacity is not the most significant drive behind why and how rebels find safe havens in the borders of other states (Lai, 2007; Hastings, 2010; Hendrix & Young, 2014).

  4. 4. NAGs select the states from which they seek support as much as states choose to support certain NAGs. Interstate hostilities, relative strength of supporter vis-à-vis target states, and ideational ties to outside states motivate NAGs to seek support within certain states without necessarily requiring direct foreign government sponsorship (San-Akca, 2016).

Main Variables

State–NAG Alliance/State Support

External state support for rebel groups takes various forms, ranging from the provision of bases for operations and training to the recognition of their cause as “just” (O’Neill, 1980; Byman, 2005). For present purposes, those types of support that directly or indirectly contribute to the survival and violent activities of a group are relevant. The NAGs dataset has information on nine types of support: safe havens for group militants; safe havens for groups’ leaders; training camps; training; arms and logistics; funds; transport of arms, military equipment, and supplies; operation of offices; and troops (San-Akca, 2015, 2016). In total, the NAGs dataset has information on 111 state supporters and 454 rebel groups. It identifies 355 cases of state–NAG alliances.

The dependent variable, external support, is coded in two ways: as a binary variable if a potential supporter state provides any type of support at all; and as a binary variable for specific types of support, such as safe havens, arms, and funds.

Interstate Hostility

A well-established finding in the existing research is instrumental; states support NAGs, if they are the enemies of enemies. A variable developed by Maoz (2007) named the Strategic Reference Group (SRG) is used to identify states that pose a security challenge to a given foci state—target state in the present text. This variable takes a value of “1” if a potential supporter and a target engaged in either a militarized dispute with each other in the last five years or a war in the last 10 years, and a “0” if there is no conflict history between a potential supporter and a target state during the period when a rebel group actively fights the target in question. There are more specific measures of interstate rivalry, such as Thompson and Dreyer rivalry data (Thompson & Dreyer, 2012). Yet, SRG provides a broader conceptualization of a state’s perception of its outside security environment.

Supporter–Rebel Group Ideational Affinity

In order to determine the ideational affinity between a rebel group and its supporter, one needs to specify the identity of each state in terms of the components of the ideational identity specified for groups. The ethnic and religious characteristics of a state do not automatically translate into its foreign policy, although they are not trivial in determining the cultural distance among countries. Each group is paired with its potential supporter in terms of whether it has ethnic and religious kin living within the borders of a given potential supporter. Furthermore, existing research indicates that it matters whether ethnic kin is a majority or a minority group within the borders of other states or whether ethnic kin has access to political resources in states where they reside (Carment & James, 1996; Davis & Moore, 1997; Saideman, 1997).

In exploring the ideational affinity between ethnonationalist and religious groups and the potential supporters, two datasets are used. The identity components in these datasets are also used to code those of rebel groups. The Ethnic Power Relations (EPR) dataset codes major ethnicities in each state (Cederman, Min, & Wimmer, 2010). Using the ethnic group labels, EPR codes the ethnic identity of each rebel group. For groups that had multiple ethnicities, the leader’s ethnicity is coded as the group’s ethnicity. Each group is then paired with (1) the major ethnic group identity and (2) the minor ethnic group identity in each potential supporter. The World Religion Project (WRP) dataset is used to code the religious identity of each group. This project has information on every state’s religious makeup (Maoz & Henderson, 2013). Each rebel group is matched with the major religion group’s identity in each potential supporter. Last, but not least, for political ideology, NAGs dataset’s ideology variable is used. This variable contains information on whether each group adopted a leftist or socialist-leaning ideology at some point during its activity. It takes a value of “1” if a potential supporter and a rebel group are both leftist-leaning and “0” otherwise. In summary, four criteria have been used in determining the common ideational ties between potential supporter states and NAGs:

  1. 1. Common major ethnic identity between states and rebels (EPR dataset).

  2. 2. Common transnational ethnic ties (EPR dataset) matching the identity of minor ethnic groups in potential supporters with rebels.

  3. 3. Common religious identity (WRP dataset).

  4. 4. A state and NAG’s sharing of socialist or leftist ideology.

Supporter–Target Ideational Affinity

The same datasets, then, are used to match each target state and potential supporter in terms of their ethnic and religious makeup as well as socialism. Furthermore, a polity score is used to calculate a lower democracy score in a given dyad of target and supporter states in order to predict the effect of joint democracy in dissuading state support of rebels (Marshall & Jaggers, 2002). One explanation behind democratic peace is related to normative drives; that is, democracies share common norms, which makes it relatively easy for them to communicate (Maoz & Russett, 1993).

Whether a potential supporter and a target share a common set of values and ideas that increase the affinity between them should influence how they treat one another. There are four main sets of shared ideas: ethnonational characteristics, democracy level, regime ideology (i.e., Marxist/Socialist9), and religion. If any of these ideational ties are common to targets and potential supporters, then this variable receives a value of “1” and “0” otherwise.

Domestic Instability

Domestic instability in a potential supporter is measured by a variable called the “instability indicator,” which was developed by the Political Instability Task Force (Bates et al., 2003). This group defines an instability event using four categories10: Revolutionary wars11; ethnic wars12; adverse regime changes13; and genocides and politicides.14 The political instability score, domins, is a binary measure given a value of “1” whenever an instability event is taking place.

Whether a state has domestic instability matters for two reasons: (1) domestic instability reduces the state’s administrative and bureaucratic capacity to act when its external security is under threat; and (2) leaders are constrained in raising resources internally to address these threats. Therefore, supporting a rebel group against one’s enemy is convenient for a leadership that is under threat internally (San-Akca, 2009, 2016). Such support might serve not only to engage with enemy indirectly, thus escaping direct accountability, but also, if blamed by target state, to rally “round the flag” by provoking public support as a reaction to external hostility.

Relative Strength of Potential Supporters vis-à-vis Targets

The relative strength of each potential supporter vis-à-vis each given target is calculated by using the Correlates of War database’s National Capabilities dataset (Singer, 1987). The dataset builds a composite index of national capabilities (CINC) by using six indicators for each country: energy consumption, iron and steel production, military personnel, military expenditure, total population, and urban population. The relative strength of a potential supporter is measured by the ratio of each potential supporter’s CINC to the cumulative CINC of a target and a supporter in a given triad. The relative strength of a potential supporter has implications for both the initial decision to provide any type of support and the level of support.

Political Party

Whether a rebel group has an associated political party. If there is an associated political party of a rebel group, which is proven to have organic links to a rebel group and engages in political activity, such as campaigning, competing in elections, and engaging in peaceful propaganda to pursue similar objectives like a rebel group, this variable is coded as “1”. If there is no such political party, it is coded as “0”. It was not required that affiliated political parties hold seats in the parliament. This variable is adopted from the NAGs dataset.

Domestic Support Base

Whether a group has a population base either within its target and/or potential supporter from which to recruit. This support base could either be an ethnic or religious minority a rebel group claims to represent or an ideologically distinct group. This variable is also from the NAGs dataset.

Other State Support

Whether a group receives provisions from other states is measured using the NAGs dataset. Number of other state supporters is included as a continuous variable ranging from 0 to 8 and as a dummy variable when a group receives support from at least 3 and more states. It receives a value of 1 if a groups is supported by 3 and more outside states other than the present state in a given triad, and receives “0”, otherwise.

Major Power

Whether or not a potential supporter is a major power. This variable is from the Correlates of War (COW) database (COW, 2016).

Potential Supporter Alliance with Other States

Using the COW interstate alliance dataset (Gibler, 2009), one gives a coding of 1 if the potential supporter has a security alliance with other states (other than the target state in question). It is important to test the effect of substitution in the states’ alliance with NAGs. In the absence of conventional state allies, states are more likely to support NAGs, which fight against their enemies.

Empirical Analysis

In estimating the state–NAG alliance onset, binary logit analysis is utilized in conjunction with Beck, Katz, and Tucker’s method (Beck et al., 1998), which helps control for the temporal dependence. Providing support in a given year influences the probability of support in subsequent years. Table 1 presents the findings on support onset.

Table 1. Logit Analysis of Support Decision, 1946–2010

Model 1

Model 2

Model 3

Model 4

Model 5


NAG Support Base

International Hostility

No Hostility

Ideational Factors


International hostility








Ideational ties









Dyadic democracy level











Relative strength











Religious ties



Ethnic ties



Socialist ties




Ideational ties










Transnational ties











Ethnic ties



Religious ties



Socialist ties




Domestic instability











Major power supporter











Alliance with other states




Political party











Domestic support base










Control Variables

Cold War



































(***) P ≤.001;

(**) P ≤.01;

(*) P ≤.05.

In parentheses are robust standard errors that are calculated by clustering the observations by triadid, that is, for each triad of target, NAG, and potential supporter. Cubic splines and consecutive years of no support are not presented on the table, but they are included in the analysis. Distances between capital cities of targets and supporters have been included as a control variable across all models; yet, they are not reported since the coefficients are almost zero and basically had little influence on support likelihood, though they are statistically significant.

The first model listed in Table 1 estimates a model for the decision to support a group, while the second model controls for the effect of the key variables after including whether or not a rebel group has a support base within the population of either target or supporter state. Model 3 runs the analysis only for the cases of state-rebel alliances, where targets and potential supporters have hostility toward each other. Model 4 runs the analysis for cases in which there was no hostility between target and supporter states. Finally, Model 5 unpacks the ideational factors for both target–supporter relations and supporter–rebel relations. The objective is to see if some type of ties matters more than others.

International hostility has a robust positive effect on the likelihood of state–rebel alliance formation across all models. This is a common finding in the existing research as well. Although not all state–rebel alliances are formed against a common enemy, states frequently support rebel groups for instrumental or security-related purposes (H1). The other equally robust and significant variable is ideational connection between states and rebels. As states and rebels share common ethnic, religious, and ideological ties, they are more likely to ally with each other. This confirms the initial framework that is proposed after building on the teachings of realism and constructivism. While states behave out of concerns for consequences and utility, they also behave out of concerns for principles. States and rebels are allied for both instrumental and normative reasons. Indeed, Model 4 shows that states support ideationally contiguous rebels even in the absence of hostility with their targets (H5). Transnational ethnic ties are also significant and robust for predicting the onset of state–rebel alliances. This finding is in line with existing research on the relationship between transnational ethnic kin and support for rebels.

Relative strength proves to be significant and positive almost across all models. States and rebels are more likely to ally with each other if a potential supporter has the ability to deal with a possible retaliation from a given target state (H2). Model 3 confirms the substitution hypothesis (H4). When supporting rebels against hostile states, potential supporters are more likely to do so if they do not have conventional state allies to rely on. This is also in line with the balancing logic of Walt (1985). States balance not only against rising powers, but also against external threats. Ideational ties between states and rebels are still significant in predicting state support of rebels against external enemies (H6). This finding is especially relevant for cases in which multiple groups are fighting against the same state and a potential supporter chooses one or many among them.

When it comes to the findings related to liberalism’s insights, democratic peace seems to have a similar effect on state support of rebels; that is, states are less likely to support rebels who fight against other democracies (H8). This is in line with the logic of democratic peace as it applies to explaining the lack of war between or among democratic states. Nevertheless, the effect of democracy disappears after controlling for the domestic population base of rebels. If rebel groups have domestic constituents who are sympathetic to their causes, in either their target or supporter states, then it does not seem to matter whether their supporters and targets are both democracies. Rebels with domestic constituents are always more likely to acquire outside state allies or supporters. The other types of ideational ties between supporters and targets, though, seem to have a more robust and negative effect on the likelihood of supporting rebels. In other words, potential supporters are less likely to ally with rebels fighting against ideationally contiguous target states (H7). Supporter–target ideational contiguity reduces the likelihood of alliance formation between sates and rebel groups.

Domestic instability has a robust positive effect on state–NAG alliances. State leaders might choose to use their support of rebels to boost public solidarity at home and outsource their foreign policy. Especially if they face opposition at home, extracting from the domestic population might cost them the office. Therefore, rebels turn out to be convenient allies (San-Akca, 2017). Whether a group has a domestic support base within the population of target or potential supporter and whether it has an associated political party are significant predictors of state–rebel alliances. States might prefer rebels, who are able to recruit and run propaganda to acquire international recognition since international recognition is the only way to justify and prolong violent campaigns against given states. Affiliated political party wings are significant for showing the rebel groups’ political face to domestic and international audiences.

Which ties matter? Are some ideational connections prioritized over others? Model 5 unpacks the various components of ideational ties used for coding ideational affinity between targets and supporters as well as between supporters and rebels. It seems that a socialist connection between supporters and targets has a dissuading effect on state support of rebels and the only type of interstate ties that matter in dissuading state–rebel alliances. Socialist states are less likely to form alliances with rebels who fight against other socialist states. By the same token, when it comes to supporter–rebel ties, socialist ties and ethnic ties prove to be significant. Religious ties do not seem to explain much of the behavior of states when it comes to cooperating with rebels. States are more likely to support rebels who represent the ethnic kin of their dominant ethnic group and have expressed socialism as their worldview. This also means that states have a tendency to support rebel groups with secular ideology rather than religiously-motivated ones.

Table 2. NAG Objectives

Model 6

Model 7

Model 8

Model 9

Topple Leader

Regime Change




International hostility









Ideational ties









Dyadic democracy level









Relative strength










Ideational ties









Transnational ties










Domestic instability









Major power supporter










Political party









Domestic support base









Control Variables

Cold War





























(***) P ≤.001;

(**) P ≤.01;

(*) P ≤.05 +P ≤.10.;

In parentheses are robust standard errors calculated by clustering the observations by triadid, that is, for each triad of target, NAG, and potential supporter. Cubic splines and consecutive years of no support are not presented in the table but are included in the analysis.

Table 2 presents the effects of key variables across distinct types of rebels in terms of their objectives. The NAGs dataset contains information on four different objectives: toppling an existing leadership, regime change, autonomy, and secession. These are not mutually exclusive categories. A NAG might aim for regime change as well as autonomy. Across all four models, interstate hostility has a robust effect on state–NAG alliances. This is in line with existing research; states are most likely to support rebels, regardless of rebels’ objectives, who fight against their enemies. Principled or ideational support is most likely to occur for rebels who seek autonomy or secession from target states (Models 8 and 9). This finding is not surprising given that most ethnic-oriented groups claim autonomy and secession. On the other hand, states do not seem to care much about their ideational contiguity with rebels if they are simply motivated to topple an unwanted leadership or regime. They behave more pragmatic by choosing to support such groups agains their adversaries. This also means that rebels, when having as their objectives the toppling of an existing leadership or changing an existing political regime, are more likely to appeal to the adversaries of their target states.

With regard to interstate ideational ties, democracy is significant only for alliance with rebels who fight targets to change the political regime. Democratic states are less likely to support rebels who fight to change the political regime in other democracies. In all other types of rebels, democracy does not seem to have a significant effect. Transnational ethnic ties have robust, significant effects on the formation of state–NAG alliances. The presence of domestic opposition and instability in potential supporters helps explain the formation of alliances with rebels who seek secession from target states. But it does not have a significant effect for supporting rebels who have objectives other than secession. In other words, if a potential supporter goes through some domestic turmoil, it is more likely to support a secessionist movement. This variable was also significant in Model 3 of Table 1 when states make a decision to ally with a group that fights against its enemy. Outsourcing one’s foreign policy is a more likely strategy if there is a risk of domestic opposition. Engaging with one’s enemy directly might jeopardize a government’s or leader’s position at home since relying on domestic population for material and human resources can be used by the domestic opposition to start a rally against government.

When it comes to ideational ties between supporter and target states, they dissuade the support of autonomy-seeking rebels. In other words, potential supporters who share common ethnic, religious, and ideological ties with the target states, of rebels, are less likely to support groups that seek autonomy from ideationally contiguous targets. This could be because once an ethnic group is in a position of power in one state, it does not want to inspire other secessionist movements within the borders of other states. If this is the case, this variable should have been significant for secessionist rebels as well, but we do not observe a significant effect of supporter–target ideational ties on support of secession-seeking rebels. The domestic support base has a robust effect across all models. It means that rebels, who rely on the domestic population within targets or supporters for recruitment, are more likely to acquire outside state supporters. This might be attributed to internationalized ethnic conflicts. Frequently, ethnic rebels have their ethnic kin in neighboring states, which puts pressure on the governments of these states to extend support to rebels.

With regard to specific types of support, Table 3 presents the findings for two sets of support. One is a combined safe haven variable that includes whether a state provides safe havens for the militants of a group and for its leaders, and also provides training camps. The other set of support is a combined variable for weapons and financial support. Across Models 10 and 11, international hostility has a robust positive effect on providing safe havens and providing weapons and funds, respectively. Democratic peace seems to apply when an alliance involves provision of weapons and funds to rebel groups. Democratic states are less likely to provide weapons and funds to groups that fight against other democracies. Ideational ties between targets and supporters reduce the likelihood of providing either of these forms of support.

Table 3. Safe Havens, Training Camps, Weapons, and Funds

Model 10

Model 11

Safe Havens and Training Camps

Weapons and Funds


International hostility





Ideational ties





Dyadic democracy Level





Relative strength






Ideational ties





Transnational ties






Domestic instability





Major power supporter






Political party





Domestic support base





Control Variables

Cold War

















(***) P ≤.001

(**) P ≤.01;

(*) P ≤.05 +P ≤.10.

In parentheses are robust standard errors calculated by clustering the observations by triadid, that is, for each triad of target, NAG, and potential supporter. Cubic splines and consecutive years of no support are not presented in the table but are included in the analysis. Distances between the capital cities of targets and supporters have been included as a control variable across all models, yet not reported since the coefficients are almost zero.

The initial categorization of states’ motives for forming alliances with rebels seems to apply for interstate relations as well. States choose not to support rebels fighting against ideationally contiguous states. This can be one way the principled alliance mechanism is at work. Model 4 of Table 1 provides further evidence for this causal mechanism. Even in the absence of external hostility, states are less likely to form alliances with rebels who fight against ideationally contiguous states. Transnational minorities influence the likelihood of providing safe havens but have no significant effect on weapons and funds’ provision (Model 11). Other variables, such as domestic support base and the presence of an affiliated political party, seem to have similar effects on the provision of safe havens and training camps and weapons and funds.

Finally, the empirical analysis so far show that all three paradigms of International Relations Theory complement each other in explaining state-rebel alliance formation. Both security-related and ideationally-motivated factors seems to drive these alliances under a given set of circumstances. Given the frequency of state-rebel alliances in the last decades, further analyses on Table 4 are warranted. Do states compete over proxies as is suggested in the beginning of this text? If so, how? Models 12 and 13 confirms that states are driven with a sense of competition with other states in making decisions about whether to support a rebel group (H3).

Table 4. Competition over Rebel Groups

Model 12

Model 13

At least one other state provision

At least three and more state provision


International hostility





Ideational ties





Dyadic democracy Level





Relative strength






Ideational ties





Transnational ties






Domestic instability





Major power supporter






Political party





Domestic support base





Other states supporting





Control Variables

Cold War






















(***) P ≤.001

(**) P ≤.01

(*) P ≤.05 +P ≤.10.

In parentheses are robust standard errors calculated by clustering the observations by triadid, that is, for each triad of target, NAG, and potential supporter. Cubic splines and consecutive years of no support are not presented in the table but are included in the analysis.

International arena witnesses a constant competition among states trying to achieve superiority to each other from the perspective of realism. As is illustrated in many historical cases of state-rebel alliances, and most recently in the case of US and Russian alliance with YPG/PYD, states compete over proxies. This behavior is anticipated if one applies the teachings of realism to the complex web of interactions between states and rebels. After the inclusion of two variables measuring whether a given rebel group is supported by other states at all and whether it is supported by more than two states, the competition hypothesis is confirmed. Model 12 shows that when states know that there are other states providing provisions to a group, they are more likely to support that group. By the same token, model 13 shows that when there is more than two states providing support to a given rebel group, another state jumping on the bandwagon is also very likely. Indeed, a state is three times more likely to support a rebel group, which is already supported by more than two states. One could anticipate that one might give up knowing that there are others providing provisions. Yet it seems to be the contrary. States compete over rebel groups as much as they compete over other instruments of power and influence at the international scene.

Further Venues of Research

Does the type of motivation influence the consequences of state–NAG alliances for international conflict and cooperation? The preceding analyses showed that states ally with NAGs out of both security-related and ideational concerns. The origins of state–NAG alliances are similar to those of interstate alliances. Yet ideology is not inferior to security concerns in bringing states and NAGs together. Future venues of research should build on these causal discoveries and address the following issues:

  1. 1. How do state–NAG alliances emerge and evolve outside of the context of civil war?

  2. 2. How does outside state supporters influence the responses of governments against ethnonational, secessionist, and revolutionary movements?

  3. 3. What kind of international system is more conducive to the emergence of state–NAG alliances?

  4. 4. Does the perceived motive behind state–NAG alliances influence the strategy pursued by armed groups, treatment of civilians, and their response to target government calls for negotiations and bargaining?

  5. 5. What are the conditions under which states compete over support of the same rebel groups?

As increasing democratization and technological advancement lead states to delegate their business to NAGs, it is about time that more space is made for nonstate armed groups in refining International Relations theory. It is essential to build a research agenda guided by systematic questions, theoretical insights, and empirical findings. Only in this way will it be possible to reach a common body of knowledge that is also useful to policymakers. Furthermore, development of effective counterterrorism and counterinsurgency instruments would benefit from such scientific knowledge to a great extent.

The international community sends signals to NAGs for collective action. If they anticipate support from a liberal state, they will be more cautious in their campaigns. The type of supporter and the relations it has with the target states might also influence the strategy pursued by target governments. If target states believe that strategic support is available, they might choose repression over accommodation given that it has to deal with the domestic proxy of its outside enemy now. On the other hand, if NAGs believe that strategic support is more dominant, depending on the signal they receive from outside states, they might be more likely to use terrorism. In contrast, if they think that ideational or principled support is the dominant paradigm, they will be less likely to use terrorism. This also explains the low level of violence committed by the more conventional NAGs, such as ETA (Euskadi Ta Askatasuna) and IRA (Irish Republican Army). They would anticipate support from neighboring outside states, which are highly democratic. In addition, it is very difficult to justify supporting NAGs, which use indiscriminate violence in the eyes of liberal societies. In contrast, the newer violent groups, such as ISIS and al-Qaeda, do not feel obligated to appeal to ideational supporters. Unlike the more conventional NAGs, they commit a high level of violence to appeal for strategic support, if they are interested in attracting support from states at all.

These international signals and their implications for state–NAG alliances are the subject matter of future research. These signals can be examined at local, regional, and global levels. If there are tensions across these three levels, NAGs might manipulate them to achieve the highest level of support from outside states. If the signals are similar from each level, there might be little room for manipulation. For example, at the global level, the signal could be more about self-determination principles, while at the regional level, the signal could be more about strategic concerns. Then, a NAG might adopt a strategy that will appeal to both strategic and principled states for alliance. All these are interesting questions awaiting answers from future research.


Since the 20th century was dominated by notions related to nationalism and self-determination rights as major forces behind state-making, it is not surprising that a significant number of NAGs emerged on the basis of these ideas. Since the territories of many states do not overlap with the ideational makeup of their societies, the result was many multiethnic states. These multiethnic states are usually home to ethnic kin in neighboring states. Therefore, the contagion of ethnic conflict, in the post–Cold War period happened mostly through intervention by states that have ethnic kin involved in internal conflicts. The interstate alliance and conflict patterns over transnational ethnic kin is best explained by Weiner’s early work, resonated by the concept of the “Macedonian syndrome” (Weiner, 1971). The preceding analysis went beyond ethnic ties among states and between rebel groups and states to explain how they influence interstate and state–group conflict and cooperation patterns.

Existing research on interstate alliances and newly emerging research on intergroup alliances both emphasize instrumental or strategic interests as the major rationale behind their formation. Yet, the preceding analyses show that states are equally driven by their ideational ties to both rebel groups and rebels’ target states when they make a decision to ally with rebels. The results provide evidence that states’ foreign policies toward rebels who fight against other states are more influenced by political ideology than by the ethnic and religious identity of their society.

After unpacking the ideational characteristics, socialist states are found to be less likely to provide support to rebels fighting against other socialist states. By the same token, democratic peace theory seems to apply to the formation of state–group alliances. Democratic states are less likely to ally with rebels who fight against other democracies. Overall, states are equally invested in forming instrumental and principled alliances with rebel groups. Although international hostility has a robust positive effect on state–group alliances, it is not the only factor motivating such alliances. States support rebels even in the absence of hostility with rebels’ target states. Whether such support in turn leads to hostility between supporters and targets is a different issue. Therefore, in contrast to the dominant view about interstate alliances that ideology or ideational factors are secondary to security concerns in driving states to ally with each other, the empirical findings so far show that states are equally motivated to form principled alliances with rebels (in the absence of security concerns).

With regard to unpacking the ideational ties between states and rebels, ethnic and socialist ties seem to drive state–group alliances rather than religious ties. This finding could be attributed to the fact that religious-oriented fundamentalist groups are more likely to take pride in not having external state sponsors. Yet, ethnic-oriented rebels can endure for long periods depending on whether they are able to secure some connections with external states. Especially, the post–World War I international environment signals potential rebel groups to mobilize around a collective action for self-determination. Since ethnic rebels try to emulate states in their search for independent states, it is reasonable for them to seek international recognition. Indeed, supporting ethnic rebels provides leverage to the international community both in controlling the level of violence they might end up committing against their target states and in encouraging the target state to search for a solution. This is hardly so for religiously motivated groups, since they are not likely to subject themselves to outside states by accepting their support.

Last, but not least, the empirical findings point to some explanations about states’ competition over rebels. Frequently, rebels manage appealing to more than a single state for support. States seem to support rebels even after knowing that they receive provision from other states. This issue alone deserves further elaboration to help explain how multiple outside state supporters influence the onset of conflict and strategy pursued by conflicting parties.


The research in this article was funded by a Marie Curie International Reintegration Grant (Proposal Ref. No. FP7-268486 and Grant ID No. REA.P3(2010)D/3202). Part of it was also funded by the Turkish Academy of Sciences—Award for Outstanding Young Scientists (TUBA-GEBIP). The author thanks Efe Can Çoban for his assistance.


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(2.) This does not mean that the theoretical framework has to be driven from existing research on state behavior for IR to preserve its place among Social Sciences as an autonomous discipline. Yet, decades-long research on state behavior offers a proper beginning to start developing such coherent body of theoretical insights on the behavior of states vis-à-vis non-state armed groups. Neither is the implication that non-state armed groups are similar to states, thus they should be evaluated from the perspective of state behavior theories. In contrast, only if we start testing these theories in the context of state-rebel alliances, it would be possible to see if they apply to explaining and predicting these parallel forms of alliances that have come to dominate world politics.

(3.) See Lake and Powell (1999) for an application of the strategic choice model to making foreign policy choices in general.

(4.) The balance of power theory is understood here as an extension of realism. Originated by Morgenthau (1963), the balancing behavior theory argues that states balance against strong powers. Walt (1987) refined this theory, arguing that states balance not only against powerful states but against threats as well.

(5.) Saideman (2002) provides a similar argument for realism’s explanation for the state support of ethnic insurgencies. Schweller (2004) provides a detailed description of the literature on alliance formation and balancing.

(6.) See Klotz and Lynch (2007) for a detailed discussion of constructivism and venues of research according to this school of thought. For a discussion of mutual construction of interests and ideational components, see pp. 86–104.

(7.) The NAGs dataset uses UCDP/PRIO Armed Conflict Dataset groups.

(8.) The NAGs, their ideational characteristics, and their objectives are available at

(9.) It is possible to go into more detail about the regime’s ideology; yet, identifying each political party in democracies and figuring out whether they have a right-wing versus left-wing ideology is beyond the scope of this article. Although democracy is not necessarily the perfect opposite of Marxism and socialism, including variables for commonly socialist dyads and commonly democratic dyads, it captures a majority of the variation across various dyads.

(10.) Directly cited from the Political Instability Task Force Problem Set Codebook, 1955–2008 (Marshall et al., 2009) available at

(11.) Episodes of sustained violent conflict between governments and politically organized challengers that seek to overthrow the central government, to replace its leaders, or to seize power in one region

(12.) Episodes of sustained violent conflict in which national, ethnic, religious, or other communal minorities challenge governments.

(13.) Major shifts in patterns of governance, including abrupt shifts away from more open electoral systems to more closed authoritarian systems; revolutionary changes in political elites and the mode of governance; contested dissolution of federated states or the secession of a substantial area of a state by extrajudicial means; or complete or near-total collapse of central state authority.

(14.) Sustained policies by states or their agents, or in civil wars, by contending authorities that result in the deaths of a substantial portion of communal or political groups.