In their seminal study “Resort to Arms,” Small and Singer (1982) defined a civil war as “any armed conflict that involves (a) military action internal to the metropole, (b) the active participation of the national government, and (c) effective resistance by both sides.” Internationalized civil wars constitute a newer classification, denoting a conflict involving organized violence on two or more sides within a sovereign state, in which foreign elements play a role in instigating, prolonging, or exacerbating the struggle. Small and Singer defined civil war as one in which a “system member” intervenes into a substate conflict involving organized violence. Although Singer and Small conceived “system members” narrowly as external sovereign states engaged in military intervention into the civil war in question, the definition has since been expanded by the Peace Research Institute Oslo (PRIO) and Uppsala Conflict Data Program (UCDP) to include other foreign actors—such as nonstate or private actors, diasporas, IOs, corporations, or cross-border kin groups—any of which can intervene to intensify a domestic civil conflict. From superpower interventions during the Cold War to more recent conflicts in Syria and Ukraine, internationalized civil wars have garnered increasing scholarly attention, primarily because they tend to be far bloodier and more protracted than noninternationalized civil wars.
How to end such wars is a problem long bedeviling the international community. Civil wars are already more difficult to end than interstate wars partly because there are more players to satisfy in civil war settings, with multiple conflict parties coexisting on a single territory, and multiple factions within each conflict party—each constituting a “veto player” that might plausibly spoil a peace agreement should the agreement not satisfy their needs. This problem is exacerbated by an order of magnitude when a civil war becomes internationalized. When outside actors get involved in a civil war, the number of veto players rises correspondingly to include not only domestic players and internal factions, but also the involved external players, which may include foreign governments, diaspora groups, foreign fighters, and/or transnational social networks.
Managing or ending internationalized civil wars is thus a highly complicated balancing act requiring attention not just to internal, but also to external veto players represented by all involved parties both inside and outside the conflict state. The traditional methods of conflict management involve electoral engineering, power-sharing arrangements, or other peace deals that seek to satisfy the aspirations of involved internal parties, while ensuring that the peace deal is “self-enforcing.” This means that it will hold up even in the absence of outside pressure. In internationalized civil wars, however, conflict managers must also satisfy involved outside actors or otherwise neutralize external conflict processes. There are multiple methods for doing this, ranging from effective border control in cases of conflict spillover to decomposing internationalized conflicts into civil and international conflicts, which are solved separately, to outright peace enforcement involving international security guarantees.
Organized violence 1989–2020, with a special emphasis on Syria
