Joining by Number: Military Intervention in Civil Wars

Abstract

Understanding why and when states militarily intervene in civil wars is crucial. Intervention can increase civil wars' severity and the strategies employed in civil wars are shaped by the possibility of military intervention. This article argues that potential military interveners react to information revealed about warring parties' intentions and relative power. Without revealed information, potential military interveners are unlikely to reconsider their initial decision to remain out of the war. Revealed information causes non-belligerent states to update their expectations about the trajectory of the civil war causing them, at times, to change their calculus about the benefits of belligerency and thus intervene. This helps explain why civil wars spread and when they do so. This explanation is tested using generalized estimating equations on a new dataset of unexpected events for the civil wars in the Correlates of War Intrastate War and PRIO Armed Conflict datasets. States often worry that civil wars, such as the ongoing Syrian conflict, will draw in outside military forces. 1 Such concerns about military intervention in civil wars are quite reasonable-three fifths of civil wars experience some level of outside involvement, often by multiple states (Findley and Teo 2006). Previous studies have found that outside involvement can alter the outcome, duration, and severity of civil wars making understanding the dynamics of intervention important for both humanitarian and strategic reasons (

Indirect Interventions in Civil Wars

“…From this perspective, the focus lies on the intervening country and its relationship towards the target country. A further academic strand explores the effects of interventionism (Shirkey 2012(Shirkey , 2016. Typical questions in this area relate to the duration (Regan 2002;Balch-Lindsay et al 2008) and severity of the civil war (Sousa 2014;Wood et al 2012) once third states are caught in the dynamics of civil wars.…”

Toward a holistic networks approach to strategic third-party intervention: A literature review

“…Additionally, potential interveners must consider the role of the target state itself in shaping their decision; internal power dynamics can influence the projected impact a third party can expect to have on the outcome of a conflict, and therefore its willingness to sign on (e.g. Carment and Rowlands, 1998; Koga, 2011; Shirkey, 2016; Gent, 2008; Nilsson, 2010). Perhaps as a result, alignment is not as predictable as other scholars may have assumed.…”

Which wars spread? Commitment problems and military intervention

“…This in turn creates both balancing concerns and opportunities to bandwagon. It may also create additional commitment problems for outside states, prompting their intervention (Shirkey, 2012a; Wolford, 2014a).…”

“…From a practical standpoint, the question matters as interstate wars which experience military intervention are longer and deadlier than those that do not (Shirkey, 2012b;Slantchev, 2004). While substantial progress has been made on which states are more likely to intervene (Altfeld and Bueno de Mesquita, 1979;Richardson, 1960;Siverson and Starr, 1991;Valeriano and Vasquez, 2010) 1 and when they are likely to do so (Joyce et al, 2014;Melin and Koch, 2010;Shirkey, 2009Shirkey, , 2012a, far less is known about which wars are likely to draw in outside states.…”