Interstate Peacekeeping: Causal Mechanisms and Empirical Effects

Peacekeeping is perhaps the international community's most important tool for maintaining peace in the aftermath of war. Its practice has evolved significantly in the past ten or fifteen years as it has been used increasingly in civil wars. However, traditional peacekeeping between states is not well understood. Its operation is undertheorized and its effects undertested. This article explores the causal mechanisms through which peacekeepers keep peace and examines its empirical effects after interstate wars. To take the endogeneity of peacekeeping into account, it also examines where peacekeepers tend to be deployed. Duration analysis shows that, all else equal, peacekeeping significantly increases the chances that peace will last. Peacekeepers can help adversaries to maintain peace by making surprise attack more difficult, by reducing uncertainty about enemy intentions, and by preventing and controlling accidents and incidents that can spiral back to war.