External Threats and Military Intervention: The United States and the Caribbean Basin

Abstract

Domestic political instability provides an incentive for external military intervention by raising the opportunity costs of nonintervention. When deciding to intervene in response to instability within its sphere of influence, a regional hegemon considers the anticipated actions of other potential interveners. In particular, a hegemon has an incentive to intervene preemptively to forestall future interventions by rival powers. Given this, military intervention will be more likely when another power provides an external threat to a hegemon’s sphere of influence. A historical examination of U.S. intervention policy and behavior in the Caribbean Basin supports the theory.