Given the appalling consequences of civil wars, why are the competing actors within a state unable to come to a settlement to avoid the costs of conflict? How might external parties affect the likelihood that a civil war begins? How do their actions affect the duration and outcome of civil conflicts that are already underway? How International Relations Affect Civil Conflict draws on three main approaches—bargaining theory, signaling theory, and rational expectations—to examine how external actors might affect the onset, duration and outcome of civil wars.