The “Carter Doctrine” advanced by President Jimmy Carter led to the establishment of a strong U.S. military security presence in the Persian Gulf region, then the source of a significant share of America’s crude oil imports. Yet currently, U.S. military power underpins security for Gulf crude oil exports that increasingly flow to Asia. Authors Gabriel Collins and Jim Krane argue in this issue brief that despite this change in trade relations, the U.S. retains an enduring interest in preserving political stability and securing oil flows from the Persian Gulf.