The Aegis Ballistic Missile Defense System (Aegis BMD or ABMD) is a United States Department of Defense Missile Defense Agency program developed to provide missile defense against short to intermediate-range ballistic missiles. It is part of the United States national missile defense strategy. Aegis BMD (also known as Sea-Based Midcourse) is designed to intercept ballistic missiles post-boost phase and prior to reentry.

It enables warships to shoot down enemy ballistic missiles by expanding the Aegis Combat System with the addition of the AN/SPY-1 radar and Standard missile technologies. Aegis BMD-equipped vessels can transmit their target detection information to the Ground-Based Midcourse Defense system and, if needed, engage potential threats using the RIM-161 Standard Missile 3 (SM-3) mid-course interceptors and the RIM-156 Standard Missile 2 Extended Range Block IV (SM-2 Block IV) or RIM-174 Standard Extended Range Active Missile (SM-6) terminal-phase interceptors. On November 17th 2020, an Aegis Ballistic Missile Defense (BMD) System-equipped destroyer, intercepted and destroyed a threat-representative Intercontinental Ballistic Missile (ICBM) target with a Standard Missile-3 (SM-3) Block IIA missile during a flight test demonstration in the broad ocean area northeast of Hawaii. Notable subcontractors and technical experts include Boeing Defense, Space & Security, Alliant Techsystems (ATK), Honeywell, Engility, Naval Surface Warfare Center, SPAWAR Systems Center, Johns Hopkins University Applied Physics Laboratory (JHU/APL), and the Massachusetts Institute of Technology Lincoln Laboratory (Lincoln Lab).