Intervention, war expansion, and the international sources of civil war

Why do some civil wars turn into interstate wars? I analyze an asymmetric information model of civil war onset, rebel-sided intervention, and interstate retaliation with endogenous stakes. Interstate war occurs when rebels believe that the threat of intervention will compel the government to acquiesce, the third party believes that the government will tolerate an intervention, but they both underestimate the government's resolve. The model also has implications for civil wars. Retaliation can deter intervention and rebellion, but intervention can compel the government to give up power, so predicting civil war requires accounting for this triadic interaction.