Third-party support in intra-state conflicts is a widespread phenomenon. In roughly three-quarters of all intra-state armed conflicts from 1975 to 2009, warring parties received external support from one or more foreign states (Högbladh et al. Reference Högbladh, Pettersson and Themnér2011). Research has found that such external interventions affect the course and outcome of conflicts, for example, by prolonging fighting (Aydin and Regan Reference Aydin and Regan2012; Balch-Lindsay et al. Reference Balch-Lindsay, Enterline and Joyce2008; Cunningham Reference Cunningham2010), raising the levels of violence employed against civilians (Wood et al. Reference Wood, Kathman and Gent2012) and even reducing post-conflict well-being (Kim Reference Kim2017). The devastating conflicts unfolding in Syria and Yemen are telling examples of how patchworks of external support complicate and intensify civil wars.
This study improves our understanding of third-party interventions by analysing how differences in the political institutions of the potential intervener affect decisions concerning whether a country intervenes in a conflict beyond its borders and, if so, with what kind of support. In spite of a vast literature on the impact of democratic political institutions on foreign policy behaviour (for a recent overview, see Gelpi Reference Gelpi2017), research on third-party interventions in civil wars has largely overlooked the constraining role that political institutions can have on decisions to intervene (for an exception, see Koga Reference Koga2011). Building on insights from research on interstate wars, in particular democratic peace theory, we argue that three institutions – competitive elections, constraints on the executive, and a critical media – raise the political costs of providing third-party support to warring parties in intra-state armed conflicts abroad. As these institutions are much stronger in democracies, they make democracies less likely than autocracies to act as third-party supporters in general, and they make democracies especially reluctant to provide costly and combat-intensive means of support such as troops and weapons. Thus, political regime type is not only important when it comes to assessing the risk of conflict onset in a country but also when estimating the risk of countries getting involved in conflicts abroad.
To investigate our propositions, we make use of the UCDP External Support Dataset (Högbladh et al. Reference Högbladh, Pettersson and Themnér2011). This data set includes detailed information on the yearly provision of different types of external support provided by third-party states to warring parties in intra-state armed conflicts in the period 1975–2009. Based on this, we construct a dyadic data set of all potential third-party states paired with all conflict countries for each year in the period 1975–2009. In accordance with our main theoretical expectation, we find that democracies are significantly less likely than autocracies to provide third-party support in intra-state armed conflicts. In addition, our analysis shows that important differences do exist between the types of support that democracies and autocracies provide, although these differences are not fully in accordance with our theoretical expectations. All main results remain robust across a range of different model specifications, including different measures of core variables, different data structures, different combinations of control variables and different estimation methods.
Third-party support in civil wars
Despite the fundamentally domestic character of intra-state conflicts, external support, where the external actor attempts to assist one of the conflicting parties to win, is more the rule than the exception (Regan Reference Regan1998, Reference Regan2002; Regan et al. Reference Regan, Frank and Aydin2009). Why do some states engage in such external support while others refrain from it, and what explains the variations between the types of external support states provide?
So far, research on the causes of third-party intervention and support has focused on the different incentives states have to interfere – be it power accumulation, protection of economic interests or shielding themselves from adverse repercussions from conflicts. A number of studies have found that third-party states are more prone to intervene when they have certain ties to the conflict country. Formal alliances (Findley and Teo Reference Findley and Teo2006; Lemke and Regan Reference Lemke, Regan and Diehl2004), economic interdependence (Aydin Reference Aydin2012; Stojek and Chacha Reference Stojek and Chacha2015), dependence on oil imports (Bove et al. Reference Bove, Gleditsch and Sekeris2016) and ethnic and colonial ties (Findley and Teo Reference Findley and Teo2006; Koga Reference Koga2011; Lemke and Regan Reference Lemke, Regan and Diehl2004) all give third-party states incentives to interfere. Furthermore, third-party intervention is more likely in particular conflicts. Studies have shown that high-intensity civil wars with a high risk of contagion (Kathman Reference Kathman2011; Lemke and Regan Reference Lemke, Regan and Diehl2004) and conflicts in which a rival or ally is already involved (Corbetta and Dixon Reference Corbetta and Dixon2005; Findley and Teo Reference Findley and Teo2006; Maoz and San-Akca Reference Maoz and San-Akca2012) attract third-party interventions. Closely connected to this, proximate states which are directly affected by negative spill-overs from conflicts are also more likely to intervene (Findley and Teo Reference Findley and Teo2006). Finally, we know that great powers intervene more than other countries (Corbetta and Dixon Reference Corbetta and Dixon2005).
However, political leaders not only have different incentives to intervene, they also face different constraints. The most obvious difference is the domestic political institutions within which leaders make their decisions (Bueno de Mesquita and Siverson Reference Bueno de Mesquita and Siverson1995; Maoz and Russett Reference Maoz and Russett1993). Only a few studies have systematically addressed differences in the political institutions of intervener countries.Footnote 1 It has been shown that autocracies intervene more often in conflicts where there is a potential to profit in the form of access to lootable resources (secondary diamonds), while democracies are more prone to provide support to rebels with strong fighting capabilities and to groups with which they share ethnic affinity (Koga Reference Koga2011). Moreover, research shows that democracies predominantly target other democracies when providing third-party support (Goldman and Abulof Reference Goldman and Abulof2016). Though these studies emphasize the importance of regime type for the study of third-party interventions, it only tells us that the political institutions of the intervener state are important when coupled with particular characteristics connected to the conflict or the target country. Absent these, we should expect no differences between democracies and autocracies. The theoretical argument we present below counters this expectation.
In addition to this lack of focus on constraints, existing research on third-party involvement also largely neglects the issue of why different states provide different types of support.Footnote 2 Most studies explain interventions with different types of military support lumped together in one category of ‘military intervention’ (see e.g. Bove et al. Reference Bove, Gleditsch and Sekeris2016; Koga Reference Koga2011). However, as different types of support can have different effects on the course and outcome of intra-state conflicts (Sawyer et al. Reference Sawyer, Cunningham and Reed2017), it is important to investigate why third parties choose to provide certain types of support.
Why political institutions matter in decisions to intervene
Although political regime type has received only scant attention in studies of third-party intervention in intra-state conflicts, the idea that political institutions matter in foreign policy decisions has been prevalent in the IR literature for decades (Bueno de Mesquita and Siverson Reference Bueno de Mesquita and Siverson1995; Gelpi Reference Gelpi2017; Maoz and Russett Reference Maoz and Russett1993). In the following, we use and refine insights from the democratic peace literature to develop an independent argument for why institutions affect the likelihood and character of third-party interventions in civil wars. Whereas most research on the democratic peace theory focuses on the benign relations between democratic countries (dyadic peace), we develop a monadic peace argument that emphasizes how three particular characteristics of democratic institutions – competitive elections, constraints on the executive and a critical media landscape – regardless of the regime type of the target country constrain decision-making on interventions in civil war. Moreover, we propose that the same logics pervade not only decisions concerning whether to intervene or not but also how to do so.
Electoral competition
The sine qua non of democracy is the holding of regular, competitive, national elections. When the people choose their leaders, incumbents have an incentive to keep foreign policy decisions closer in line with the majority of the electorate (Bueno de Mesquita et al. Reference Bueno de Mesquita1999). Indeed, research shows that mistakes in the international arena can have consequences not only for results at regularly occurring elections but also for popular support between elections (Bueno de Mesquita and Siverson Reference Bueno de Mesquita and Siverson1995; Gelpi Reference Gelpi2017: 1932–1936). Thus, popular discontent with foreign policy decisions may have a direct bearing not only on the political survival of a democratic government but also on its general political manoeuvrability (Tomz and Weeks Reference Tomz and Weeks2013: 850).
We argue that the shadow of competitive elections also has ramifications for how democratic leaders view interventions in intra-state conflicts abroad. Fighting wars is always difficult to justify. Numerous studies show that citizens are sensitive to costs, especially casualties, when forming opinion on whether to support or oppose engagement in armed conflicts (Gartner Reference Gartner2008; Gelpi et al. Reference Gelpi, Feaver and Reifler2009; Karol and Miguel Reference Karol and Miguel2007). Likewise, we know that support for military actions plummets if voters do not feel that a mission is necessary to uphold national or international security (Hayes Reference Hayes2009; Russett Reference Russett1994: 38–39). In this light, interventions in civil wars should be particularly difficult to justify because the survival of the nation is rarely at stake. Furthermore, as interventions in civil wars abroad often become costly and messy affairs, we expect public dissatisfaction to be a real concern for decision-makers within democratic third-party states.
We do not argue that electorates in democracies see no benefit in civil war interventions at all. For example, voters might support interventions that aim to promote democracy or stop mass atrocities. We simply argue that such concerns seldom outweigh the costs of intervention for a majority of the electorate. In other words, the majority is rarely ready to fight for these objectives if it means that the nation must incur substantial costs in the form of casualties or a reduction of spending on welfare (De Mesquita and Downs Reference De Mesquita and Downs2006: 631).
Autocrats do not have the same constraints. This is not to say that autocrats do not face audience costs (Lai and Slater Reference Lai and Slater2006; Weeks Reference Weeks2012), nor that the relevant audiences do not affect decisions concerning third-party interventions (Kinne Reference Kinne2005). However, as authoritarian rulers can manipulate elections (or cancel them altogether) and stifle public opposition through repression, the burden of vertical accountability weighs much more lightly on their shoulders. In contrast to democratic governments, they need not fear repercussions from a disgruntled public and therefore rarely devote the same concern to avoiding potentially costly and difficult-to-justify interventions in conflicts abroad.
Checks on the executive
Democratic leaders also face more horizontal constraints than their autocratic counterparts – this also applies when making decisions about intervention in civil wars. In many democracies, the parliament must first consent to the deployment of troops abroad or approve budgets for military operations (Maoz and Russett Reference Maoz and Russett1993: 625–626). Furthermore, once approved, spending will remain under the scrutiny of parliamentarians, non-partisan bureaucrats and audit agencies. For example, in the US, the president can initiate a civil war intervention on his own, but both houses of Congress must approve military budgets and often stipulate how money is spent. Similarly, in a number of European countries, including Austria, Denmark, Ireland and Spain, the government cannot send troops abroad without the prior passing of a regular law in parliament (Born et al. Reference Born, Fuior and Lazzarini2007). These formal institutional constraints are important in themselves. But when coupled with the vertical constraints and the expected public reluctance towards civil war interventions discussed above, they are likely to bind even tighter (Tomz and Weeks Reference Tomz and Weeks2013: 850). When opposition parties and candidates, and even members of the government parties, sense defiance among the general public, they are likely to make more active use of their veto powers to capitalize politically (Gelpi Reference Gelpi2017: 1936).
Autocrats, on the contrary, only need support from the most powerful people in their ruling coalitions – and most often without the hassle of formalized decision-making processes (Svolik Reference Svolik2012: 197). In addition, constitutional stipulations that constrain the executive in the foreign policy domain are frequently either ignored or done away with over time. The recent Russian intervention in the Syrian civil war provides a telling example. The surprise engagement in September 2015 was preceded neither by discussion of the issue in public media nor by debate in the Russian parliament. Moreover, once President Vladimir Putin announced the decision, parliamentarians willingly played along and applauded every aspect of the operation (Balmforth Reference Balmforth2015). Putin never had to justify or win the broad support for the decision to send Russian troops to far-away Syria to fight for the survival of the oppressive Assad regime. Without the constraint of horizontal accountability that democratic governments face, the freedom to engage in third-party interventions is much wider for authoritarian leaders.
Critical media
A third defining character of democracies is a free and pluralistic media. This particular institution has two consequences for decisions concerning third-party interventions that feed back into the first two mechanisms presented above. First, it makes it more likely that the financial, humanitarian and political downsides of an ongoing – or a potential future – intervention come to the awareness of the public and the opposition (Fearon Reference Fearon1997; Schultz Reference Schultz1998, Reference Schultz1999). Indeed, experiments show that citizens do update their attitudes towards a conflict if exposed to new, relevant information (Gartner and Gelpi Reference Gartner and Gelpi2016). Knowledge of negative consequences of an intervention may therefore spur or fuel popular discontent and it can inspire the opposition to politicize the issue and perhaps make use of their formal veto powers. Thus, a critical media can augment the effect of the first two mechanisms. Second, the existence of a free and critical media forces political leaders to consider carefully how they justify an intervention. Motivations such as protecting oil interests, supporting a corrupt government in order to maintain an important ally, or deliberately prolonging a civil war to weaken a foe will not be an easy sell in a democratic context.
In combination, these two concerns mean that democratic leaders face a higher risk of attracting undesirable, critical attention from political opponents and the public at large in connection with interventions abroad. The anticipation of incurring reputational and political costs as a result of negative media attention probably makes democratic leaders more hesitant to intervene in the first place. President Clinton's hasty decision in October 1993 to withdraw US forces from Somalia exemplifies the costs that democratic leaders fear to incur. Not only did the pictures of a US soldier being dragged through the streets of Mogadishu outrage the general public, they also led to heated recriminations in Congress over the wisdom of the intervention (Bolton Reference Bolton1994). Indeed, ever since, the Somali incident has figured prominently in the public debate as a reminder of the potential high costs associated with interventions (Brunk Reference Brunk2008), thus illustrating how an open media environment constrains democratic leaders’ decisions about interventions.
On the contrary, most autocracies do not have an open discussion on foreign policy issues nor an independent and pluralistic media (Stier Reference Stier2015). Usually, state-controlled media and the majority of the political establishment follow the official line of the regime (Stockmann and Gallagher Reference Stockmann and Gallagher2011). If opposition is voiced, it is normally done so by marginalized regime critics or by smaller media outlets with minimal impact on public opinion (for an example, see LaPorte Reference LaPorte2015: 349). Consequently, authoritarian leaders need not fear that details concerning the negative consequences of a civil war intervention come to the awareness of the public nor that their justification of the intervention will be seriously contested. Again, the Russian support to President Assad in the ongoing civil war in Syria provides a telling example. Not only does the Putin regime consistently manipulate the official death toll (Reuters 2017), it also refuses to publish figures on the costs of its operation (Bocharova et al. Reference Bocharova, Mukametshina and Nikolski2017). Nonetheless, the dominant media within Russia remain silent.
To recapitulate: we expect countries with democratic institutions to be less inclined than authoritarian countries to send support to intra-state armed conflicts abroad. The three mechanisms we have presented each work independently, but they also reinforce each other and thus strengthen the relationship further. On this basis, we form our first, primary hypothesis:
Hypothesis 1: Democracies are less likely than autocracies to intervene in intra-state armed conflicts.
Types of third-party support
We should not expect democratic leaders to be only less likely to initiate civil war interventions in general. In the following, we argue that the three same mechanisms also constrain democratic leaders in terms of how they engage in interventions when they do decide to interfere. Specifically, we expect that democracies will be less likely to provide combat-intensive types of support, such as sending combat troops and weapons, as opposed to providing more indirect support types such as training, intelligence, logistical support and so on.
Sending combat troops to fight alongside one or more warring parties in an intra-state conflict is arguably the most visible and often most costly type of support a third-party state can provide. However, the visibility and the perceived costliness of such an involvement is highly dependent on the strength of the three institutional constraints emphasized in this article. As the Russian intervention in Syria shows, autocrats can deploy and maintain troops without public discussion of the wisdom and necessity of such an involvement and without the nagging criticism of opposition politicians. In contrast, democratic leaders must always be ready to face the anger of the electorate and the scrutiny of the opposition and the media when the country's boys are brought home in coffins (Gartner Reference Gartner2008; Gelpi et al. Reference Gelpi, Feaver and Reifler2009; Karol and Miguel Reference Karol and Miguel2007).
Provision of weapons is also a highly visible support type. Though democratic leaders do not have to worry about casualties on their own side when delivering weapons to warring parties, the provision of the equipment necessary for killing opponents and destroying infrastructure does not square well with democratic ideals of non-violent conflict resolution, just war and the protection of civilians (Christensen Reference Christensen2015). Again, this means that democratic leaders must invest heavily in justifying such partisan support and not least defending the actions and goals of those groups that receive the weapons (Schmitt Reference Schmitt2014). The protracted discussion of whether or not to send arms to the Ukrainian government in its fight against Russian-sponsored separatists in the east indicates that such dynamics of constraints clearly influence decision-makers in democracies (Schmitt and Kramer Reference Schmitt and Kramer2017). Again, due to the stifled political context and the much weaker vertical accountability, rulers in autocracies do not face the same needs for public justification, and often the provision of weapons can effectively be kept secret from the public.
Turning to more indirect support types such as access to territory or provision of logistics, intelligence, training and expertise, the expectations are less clear-cut. Indirect support types are less likely to be financially burdensome, less likely to result in casualties and are rarely subject to prior formal approval in parliament – all of which make indirect support less problematic for democracies. Still, even indirect support – if poorly justified – can attract the attention of the opposition or trigger public debate. On this basis, we still expect democratic governments to be different from their authoritarian counterparts, but less so than for the other two support types. Thus, we formulate two additional hypotheses:
Hypothesis 2a: Democracies are less likely than autocracies to intervene in intra-state armed conflicts by providing combat-intensive means of support such as troops and weapons.
Hypothesis 2b: Democracies are less likely than autocracies to intervene in intra-state armed conflicts by providing indirect support such as intelligence and training, but the effect of democracy on indirect support is smaller than the effect of democracy on combat-intensive support types.
Methods and design
To test our theoretical expectations, we combine data on intra-state armed conflicts, potential intervener countries and the dyadic relations between them. We construct a dyadic data set consisting of all countries with armed intra-state conflicts in the period 1975–2009 identified in the UCDP Armed Conflict Dataset (Gleditsch et al. Reference Gleditsch2002)Footnote 3 paired with all independent countries in the world each year.Footnote 4 Thus, we consider all countries in the world, except for the conflict country, as potential interveners in a given year. This strategy reduces the risk of selection bias compared with only analysing a subset of ‘relevant’ interveners, and it is also the most common empirical strategy in research on third-party interventions (Bove et al. Reference Bove, Gleditsch and Sekeris2016; Findley and Teo Reference Findley and Teo2006; Koga Reference Koga2011; Stojek and Chacha Reference Stojek and Chacha2015). As a supplement to the dyad structure used in the main analyses, we also present monadic analyses in the online Appendix.
Dependent variable
To identify third-party support from foreign states in intra-state armed conflicts we use the UCDP External Actor Dataset (UESD) (Högbladh et al. Reference Högbladh, Pettersson and Themnér2011),Footnote 5 which contains disaggregated information on 10 different types of third-party support to all warring parties listed in the UCDP/PRIO Armed Conflict Dataset. The UESD is thus more comprehensive than the data sets previously used in the literature; namely, Regan's intervention data (Regan Reference Regan2002) and the International Military Interventions Dataset (Pearson and Baumann Reference Pearson and Baumann1993; Pickering and Kisangani Reference Pickering and Kisangani2009).
External support is defined as ‘warring or non-warring support to a primary party that is given to assist it in an ongoing armed conflict’ (Högbladh et al. Reference Högbladh, Pettersson and Themnér2011: 5). In line with our theoretical focus, the data only include partisan interventions, where support is given with the intention to strengthen a party in the conflict. This also means that UN-sponsored peacekeeping operations and ‘action against foreign rebel groups that are merely carried out to protect one's sovereignty’ (Högbladh et al. Reference Högbladh, Pettersson and Themnér2011: 5) are left out. The UESD contains 145 intra-state armed conflicts in 89 countries, totalling 973 conflict country years. In almost three-quarters of these conflicts (108 out of 145), state-sponsored third-party support was provided to one or more of the warring parties.Footnote 6 When reorganized into dyads of conflict country and potential intervener country, third-party support is present in 2,356 (1.51%) dyad years out of the total 155,750 dyad years in the period 1975–2009.Footnote 7
To test hypotheses H2a and H2b, concerning the type of third-party support provided, we combine the UESD's 10 different support types into three overall categories that match our theoretical distinction between combat-intensive support and indirect combat support. In the former category, we distinguish between troop support, which includes all types of troops fighting alongside one of the warring parties, and weapons support, which includes donations, transfers and loans of weapons and ammunition (Högbladh et al. Reference Högbladh, Pettersson and Themnér2011: 6–8). In the latter category, we include funding/economic support such as military loans and grants, access to intelligence material, material/logistics such as vehicles and uniforms, access to territory, access to military/intelligence infrastructure and training/expertise (Högbladh et al. Reference Högbladh, Pettersson and Themnér2011: 6–8).Footnote 8 In years where a third-party state is involved in several types of support to one or more warring parties in the same country, we classify cases hierarchically.Footnote 9 Based on this coding, weapons support is the most common support type (963 dyad years), while troop support is the least common support type (617 dyad years). Cases of pure indirect support fall in between the two others (776 dyad years). In the online Appendix, we present results with alternative categorizations of support.
Table 1 lists the 10 most frequent sender countries and target countries of third-party support based on all 2,356 dyads of support in the data. The US is, not surprisingly, an exceptionally active supporter involved in almost three times as many dyads of support as the second-most active third-party state, Russia (the Soviet Union). More importantly, we note that eight out of 10 of the most frequent supporter countries are autocracies. For example, Cuba under Fidel Castro supported warring parties in several Latin American and African conflicts during the Cold War period (e.g. Nicaragua, El Salvador, Ethiopia, Angola, Mozambique, Zimbabwe and South Africa) with weapons, training and sometimes even combat troops (Angola and Ethiopia). Libya under Muammar Gaddafi was another very active third-party supporter, especially in North Africa. Finally, Iran and Syria have been heavily engaged in support throughout the Middle East. Among less frequent interveners we find several autocracies but also some democracies including the UK, Israel, Italy, Australia and India.
Table 1. Top 10 Third-Party Supporters and Target Countries 1975–2009
Note: Observations are dyad years of support.
Turning to the most frequent targets of support, Iraq and Afghanistan top the list. The majority of dyad years of support for these countries relate to the conflicts following the US-led invasions in 2001 and 2003, in which a substantial number of countries, mostly democracies, provided third-party support.Footnote 10 Somewhat surprisingly, the US itself is also present on the list. The reason is that after the 9/11 terrorist attacks, the US government fought al-Qaeda on its own territory, and during this conflict Washington received ample support from its allies abroad. Again, by far most of these third-party supporters were democracies. It is debatable whether these three armed conflicts connected to the War on Terror, Afghanistan (2001–), Iraq (2003–) and the US (2001–), should be considered as intra-state armed conflicts, as they are clearly qualitatively different from the other 142 intra-state armed conflicts in the data set. The issue is particular pertinent for this study because these special conflicts are also characterized by a very large number of instances of third-party support. We choose to exclude all three conflicts from our main analyses but also run a number of robustness checks where they are included (see below). Beyond the most frequent targets of support, which are located in Africa and the Middle East, the data include target countries from all parts of the world such as Cambodia, Nicaragua, Philippines, Azerbaijan, Sri Lanka and Argentina.
Independent variable: political regime type
Following the convention in conflict studies, we identify regime type using the revised polity2 scale from the Polity IV data set (Marshall et al. Reference Marshall, Gurr and Jaggers2017).Footnote 11 The six components, from which the polity2 scale is constructed, directly or indirectly reflect the regime-type characteristics that we emphasized in our theory.Footnote 12 To test our hypotheses, we create a set of dummy variables that distinguish autocracies (polity2 score −10 to −6) from anocracies (polity2 score −5 to 5) and democracies (polity2 score 6 to 10). In our data, 60,196 dyad years (41.8%) have a democratic potential intervener, 50,185 dyad years (34.9%) have an autocratic potential intervener, and 33,477 dyad years (23.3%) have an anocratic potential intervener. We also present results using the continuous 21-point polity2 scale (rescaled to range from 1 to 21).
We are aware of the criticism raised against the polity2 scale (Cheibub et al. Reference Cheibub, Gandhi and Vreeland2010; Treier and Jackman Reference Treier and Jackman2008). To make sure that our results do not depend on the Polity data itself, the online Appendix presents robustness checks with an alternative aggregate measure of democracy from the Varieties of Democracy (V-Dem) data set (Coppedge et al. Reference Coppedge2016).
Control variables
We control for conflict country confounders, supporter country confounders and dyadic confounders. As for the former, we include three controls. The first is the conflict country's total annual oil production in metric tonnes (Ross and Mahdavi Reference Ross and Mahdavi2015) since access to natural resources, especially oil, is argued to attract third-parties in general and autocracies in particular (Bove et al. Reference Bove, Gleditsch and Sekeris2016; Koga Reference Koga2011). We also include a control for rebel group strength since democracies might be particularly prone to provide support to strong rebel groups (Koga Reference Koga2011: 1146–1147) and since rebel group strength might affect the probability of external support in general.Footnote 13 We use the NSA data set (Cunningham et al. Reference Cunningham, Gleditsch and Salehyan2013) to identify the strongest rebel group vis-à-vis the government on an ordinal scale ranging from 1 (much weaker than the government) to 5 (much stronger than the government).Footnote 14 Lastly, we control for the conflict country's regime type, polity (conflict country), using the full 21-point polity2 scale (Marshall et al. Reference Marshall, Gurr and Jaggers2017). The latter ensures that our results are not driven by democracies only intervening in democratic countries, which typically experience fewer intra-state conflicts, and autocracies only intervening in autocratic countries, which have more intra-state conflicts.
Turning to supporter country confounders, we include a control for major power status, since major powers are more likely to intervene (Corbetta and Dixon Reference Corbetta and Dixon2005) and since most major powers are democracies. Using the Correlates of War State System Data, we create a dummy variable indicating whether a country was considered a major power (1) or not (0) (Correlates of War Project 2016).
We control for five potential dyadic confounders. Using the ICOW Colonial History Data Set (Hensel Reference Hensel2014),Footnote 15 we create a dummy variable, colonial relations, indicating whether the conflict country was a former colony of the potential intervener country (1) or not (0). Intervention is more likely in a former colony because of political and cultural linkages (Koga Reference Koga2011; Lemke and Regan Reference Lemke, Regan and Diehl2004; Stojek and Chacha Reference Stojek and Chacha2015), and most countries with prior colonial possessions are today democracies. To capture alliance bonds, we use the Correlates of War Formal Alliances Dataset to create a dummy variable, alliance, indicating whether any type of alliance exists between the conflict country and the potential intervener country (1) or not (0) (Gibler Reference Gibler2009).Footnote 16
Since countries often shy away from involvement in other countries that are stronger than themselves, and since democracies often have stronger capabilities than autocracies, we also include a control for the capabilities ratio between the two countries (Bove et al. Reference Bove, Gleditsch and Sekeris2016; Corbetta and Dixon Reference Corbetta and Dixon2005; Findley and Teo Reference Findley and Teo2006; Koga Reference Koga2011). We divide the Composite Index of National Capability (CINC) score of the conflict country by the CINC score of the potential intervener country using the Correlates of War National Material Capabilities Dataset (Singer et al. Reference Singer, Bremer, Stuckey and Russett1972).Footnote 17 We also control for the distance between the borders of the conflict country and the potential intervener country in kilometres at the closest point using the CShapes data set (Weidmann et al. Reference Weidmann, Kuse and Gleditsch2010). Most studies of intervention include a control for distance since the cost of intervention rises the further away a conflict is (Bove et al. Reference Bove, Gleditsch and Sekeris2016; Koga Reference Koga2011; Stojek and Chacha Reference Stojek and Chacha2015). However, distance is particularly important in our analysis because civil wars tend to cluster in regions with more autocracies. Thus, failing to control for distance might lead us to overestimate the effect of democracy. Finally we include a control for the total sum of bilateral trade in millions of current US dollars from the COW bilateral trade data (Barbieri et al. Reference Barbieri, Keshk and Pollins2009),Footnote 18 since democracies often have higher levels of trade, and since trade has been argued to increase the probability of intervention (Stojek and Chacha Reference Stojek and Chacha2015).
Lastly, we introduce two time controls. First, we control for differences between the Cold War period and the post-Cold War period as third-party interventions could be expected to be more frequent during the geopolitically contested Cold War period (Regan Reference Regan1998: 767), which might coincide with changing incentives to intervene for democracies and autocracies. We construct a dummy variable, Cold War, which takes the value of 1 until 1989 and 0 from 1990 and onwards. Second, to control for omitted variable bias correlated with time, we include time since intervention, which counts the years since the last intervention in the same dyad.Footnote 19 For example, a country that has recently been engaged in an intervention might have more knowledge concerning local contexts and challenges, which could increase the likelihood of conducting another intervention. We lag the variables alliance, bilateral trade, polity (conflict country) and oil production one year, since they may be affected by the provision of third-party support. We also log-transform the continuous control variables capabilities ratio, bilateral trade, distance and oil production to reduce the influence of outliers and scale down the variance.Footnote 20
Modelling
To test H1, in which the outcome is binary (support or no support), we follow common practice in the literature on third-party interventions (e.g. Kathman Reference Kathman2010; Koga Reference Koga2011; Regan Reference Regan1998) and use logit models with robust standard errors clustered on the dyad. In the online Appendix, we also show results using linear probability models with fixed effects in a monadic data structure as well as probit models. In testing H2a and H2b, we use multinomial logit models as the dependent variable has four separate outcomes: no support, troop support, weapons support and indirect support. Multinomial logit is a common estimation technique in studies on conflict outcomes (e.g. Salehyan et al. Reference Salehyan, Gleditsch and Cunningham2011) as well as third-party interventions (e.g. Koga Reference Koga2011). The estimates in the multinomial models show the effect of the predictor relative to the baseline outcome (no support).
Results
First, we investigate our main expectation, H1, stating that democracies are less likely than autocracies to intervene in civil wars. The results of Model 1 in Table 2 show that democracies are, as expected, substantially and significantly less likely than autocracies to provide third-party support to warring parties in intra-state armed conflicts. With all controls included, the log-odds of third-party support is 0.535 lower for democracies compared with autocracies. The results in Model 1 furthermore show that democracies are slightly less likely to intervene than anocracies. However, this difference is not statistically significant (see online Appendix). This indicates that the main constraining effect of democratic institutions is realized already when countries are partly democratic. We discuss this further below.
Table 2. Logit and Multinomial Logit Analyses of Regime Type and Third-Party Support 1975–2009
Notes: Logit and multinomial logit models with robust standard errors clustered on dyads in parentheses. Autocracy is the reference category in Model 1 and Model 3. The baseline outcome category in Model 3 and Model 4 is ‘no support’. a log transformed. blagged 1 year. Afghanistan 2001–, Iraq 2003– and US 2001– are not included as conflict countries. Made in Stata 14. +p < 0.1; *p < 0.05; **p < 0.01; ***p < 0.001 (two-tailed).
To illustrate the substantive effect of regime type we compare the predicted probabilities of democratic and authoritarian third-party support in Model 1. The average predicted probability of third-party support is 1.68% for autocracies, while it is only 1.11% for democracies.Footnote 21 In other words, dyad years with an autocratic potential intervener are 52% more likely, on average, to experience third-party support than dyad years with a democratic potential intervener. This is a substantial effect; larger than the effect of alliances (39% increase in probability) but smaller than colonial relations (89% increase in probability). As a further illustration of the marginal effect of democracy, we present three empirical examples of intervention-prone dyads in the online Appendix: Cuba–Nicaragua (1978), Zimbabwe–DR Congo (1998) and Spain–Morocco (1979). In all three cases, the predicted probabilities of supplying third-party support are more than 60% higher with an autocratic regime compared with a democratic regime, all else constant.
Turning to the control variables, Model 1 yields similar results to many previous studies of third-party support (Bove et al. Reference Bove, Gleditsch and Sekeris2016; Kathman Reference Kathman2010; Koga Reference Koga2011; Regan Reference Regan1998, Reference Regan2002; Stojek and Chacha Reference Stojek and Chacha2015). As expected, major powers and countries relatively stronger than the conflict country are more likely to intervene. Alliances, pacts, colonial relations and bilateral trade also increase the probability of third-party support, while distance decreases it. Running counter to the expectations of some previous studies, we note that rebel group strength does not significantly affect the probability of third-party support, while oil production significantly decreases the probability of third-party support. Finally, we see that third-party support was more likely during the Cold War than in its aftermath.
In Model 2, we test H1 using the full 21-point polity2 scale as the independent variable. The results again corroborate our theoretical expectations. The more democratic a country is, the less likely it is to provide third-party support to one or more warring parties in an intra-state armed conflict. On average, a one-unit increase in the polity2 score of a potential intervener country reduces the log-odds of providing third-party support by 0.0323. The average predicted probability of third-party support decreases continuously from 1.74% for a fully autocratic potential intervener country to 1.05% for a fully democratic potential intervener country. Thus, the average predicted probability of third-party support is 65% larger in dyad years with fully autocratic potential intervener countries than in dyad years with fully democratic potential intervener countries.
As mentioned earlier, the results in Model 1 showed only slightly different likelihoods of third-party support between anocracies and democracies. Thus, one could suspect the existence of an exponentially decreasing relationship between the level of democracy and the probability of third-party support. However, using a log-transformed version of the polity2 scale reveals a very similar model fit to Model 2. This suggests that the probability of providing third-party support decreases constantly across the polity2 scale (see online Appendix for more details).
Next, we turn to hypotheses H2a and H2b, concerning different types of support provided by democracies and autocracies. The results of Model 3 show that democracies are significantly less likely than autocracies to provide weapons support, as expected in H2a, but they are even less likely to provide indirect support, which goes somewhat against the expectation in H2b. When it comes to the provision of troop support, the log-odds of −0.233 in Model 3 indicate that democracies are less likely than autocracies to provide troop support as expected in H2a. However, the difference between democracies and autocracies is not statistically significant. The results are similar in Model 4, which tests H2a and H2b using the full 21-point polity2 scale as the independent variable. The more democratic a country is, the less likely it is to be engaged in weapons support and indirect support. Countries that are more democratic are also less likely to provide troop support, but again the effect remains statistically insignificant. On the one hand, these results indicate an even stronger effect of institutional constraints than we expected. Even for the less visible and less costly types of support that are included in the category of indirect support, we find that the constraints of democratic institutions matter. On the other hand, if democratic leaders are more constrained than autocratic leaders in sending even indirect support types, why are democracies not significantly different from autocracies in their likelihood of providing troops, which is the most costly type of support?
One possible explanation is that the results regarding troops are caused by omitted variable bias. Since the provision of combat troops is expensive, and as most democracies are richer than autocracies, it could be that autocracies provide combat troops less frequently due to pure fiscal restraints. However, adding a control for the level of wealth of the potential intervener country (GDP per capita) does not change the overall results in Model 3, although it does increase the effect of democracy substantially on all support types. It could also be that our finding is a result of how troop support is coded in the UESD data set. As mentioned, the category includes all types of troops fighting alongside a warring party. Thus, it is possible that while autocracies primarily provide larger-sized regular units, democracies mainly provide smaller units such as special forces, which are less likely to result in major casualties and draw public attention. More fine-grained data is necessary to investigate this. A third potential explanation for the insignificant finding on troop support is that there is simply too little variation in the time period under investigation. In Model 3 with all control variables included, we have 127 dyad years with troop support, 762 with weapons support, and 606 with indirect support. Only 19 of the 127 observations of troop support have a democracy as the sender country, 55 come from anocracies and 53 from autocracies. These are relatively small differences in outcome, which means the results regarding troops could be sensitive to even minor changes in the time period under investigation, changes in the coding, or changes in the model specifications. Underlining the latter point, we find that democracies are, as expected, significantly and substantially less likely to provide troop support than autocracies when no control variables are included (see online Appendix). In sum, due to the relatively small number of outcomes, we should be careful in extrapolating the results regarding troops.
Mechanism
As a final step, we make a first attempt at investigating the mechanism of the argument using three separate indicators from the V-Dem data set to measure each of the three institutional constraints emphasized in the theory. Specifically, we use the Clean Elections Index as a measure of electoral competition, the Horizontal Accountability Index as a measure of checks on the executive, and the Alternative Sources of Information Index as a measure of a critical media environment (Coppedge et al. Reference Coppedge2017).Footnote 22 The coefficient plots in Figure 1 illustrate the results (see online Appendix for more details). We find that electoral competition and a critical media individually decreases the probability of providing third-party support as expected (Panels A and B), while checks on the executive behaves as expected but does not reach statistical significance (Panel C). However, when all three constraints are included in the same model (Panel D), thus controlling for each other, only critical media has the expected effect. In sum, this initial analysis of the mechanisms indicates that a critical media environment may in fact be the most important constraint in decision-making about third-party support to actors in intra-state armed conflicts.
Figure 1. Logit Analyses of Institutional Characteristics and Third-Party Support, 1975–2009
Note: Coefficient estimates from logistic regression models with 95% confidence intervals.
Robustness
Apart from the results regarding troop support, the effect of democracy is robust across a wide range of different model specifications (see all results in the online Appendix). Replacing Polity with a different, independently coded, democracy indicator, the Electoral Democracy Index from V-Dem (Coppedge et al. Reference Coppedge2017), yields similar results to our main analyses both in terms of significance levels and effect sizes. When distinguishing between support for governments and rebels, we see that democracies are significantly less likely than autocracies to provide support to either type of receiver. However, the negative effect of democracy is stronger for rebel support. This further underscores the effect of democracy as one might expect the reputational costs of rebel support to be greater than those for government support. Excluding all major powers, or only the super-powers, led to similar results. Likewise when using probit and multinomial probit models instead of logit models. Analysing only onsets of third-party support and using alternative categorizations of support types also results in similar findings. Furthermore, we find that democracies are less likely than autocracies to provide all subcategories of indirect support, except for material/logistics support.
We also see largely identical results when restructuring the data into a country-year format using logit and multinomial logit models as well as linear probability models with country fixed effects. Even though these models lack the dyadic control variables because of the country-year format, the results greatly increase our confidence in the effect of regime type. In particular this is the case for the fixed effects models, which only use within-country variation and thus have no risk of country-specific time invariant omitted variable bias. Further, to make sure the results are not sensitive to specific control variable specifications, we re-ran all models excluding each control variable individually and all control variables together. We also tested different combinations of log transformations and lags, and tried an alternative measure of natural resources (oil reserves instead of oil production). All results were similar to our main analyses, except for the exclusion of distance and time since intervention. When removing distance, the effect size and significance of democracy increases across all models, and democracies also appear significantly less likely to provide troop support than autocracies. In contrast, when time since intervention is excluded, the effect of democracy becomes slightly less significant in all models. We discuss both results in the online Appendix.
In the online Appendix, we also present results including the War on Terror cases (Afghanistan 2001–, Iraq 2003– and US 2001–). Many democracies were involved in these conflicts.Footnote 23 In Afghanistan alone, 37 different democracies were active at the peak in 2008. By comparison, across the 142 intra-state armed conflicts in our main analyses, no conflict had more than three democracies involved in the same year. As expected, including these cases affects our results markedly. Democracies are still less likely than autocracies to provide third-party support, but the effect is not significant. These results indicate that democratic constraints can be overcome under special circumstances, such as when many democracies join forces and thus share the costs and diffuse the burden of responsibility.
Conclusion
Intra-state armed conflict is the most dominant form of conflict in the world today and will most likely remain so in the future. In this article, we have shown that when such conflicts rage, potential interference by outside states is shaped by the domestic political constraints that decision-makers in third-party states face. Democratic third-party states behave markedly differently from their authoritarian counterparts: they provide support to warring parties less often and in different ways. These results have important implications for our understanding of civil wars and for how foreign policy decisions are made across different regime contexts. Given that conflicts with third-party intervention are known to last longer and be more violent, it is crucial that we understand how the political institutions of third-party states shape their propensity to get involved and the means with which they are most likely to intervene. Future studies could therefore investigate whether interventions by democracies have similar consequences to those of autocracies for conflict intensity and duration. Alternatively, they could look more into the contextual factors that can make the institutional ties binding democratic governments vary, or analyse what domestic factors cause different types of third parties to pull out of a conflict. Finally, scholars might explore whether democratic third-party interventions produce different regime outcomes in the conflict state in the longer run.
Supplementary information
To view the supplementary information for this article, please go to https://doi.org/10.1017/gov.2020.19.
Acknowledgements
This research was supported by a grant for the project CODE (Conflict and Democratization, 4110-00002B) from the Innovation Fund Denmark. The authors would like to thank Jun Koga Sudduth, Svend-Erik Skaaning, Niklas Karlén, participants at the workshop on International Dimensions of Political Instability and Conflict at Aarhus University 2017, participants at the Danish Political Science Association Annual Meeting 2017 and three anonymous reviewers for thorough and helpful comments.
