U.S. government security along the U.S.–Mexican border has been increasingly militarized. This domestic militarization has been influenced by U.S. government military intervention abroad. Preparing for and executing foreign interventions involves investing in physical and human capital to effectively coerce and control the target population. The U.S. government’s “war on drugs” and “war on terror” created the conditions for this capital to be repurposed for domestic use in border-security efforts. While foreign policy created the conditions for border militarization, border militarization has also influenced foreign interventions. This article explores the symbiotic relationship between U.S. border militarization and foreign policy.