The Aegis Ballistic Missile Defense System is a US Department of Defense Missile Defense Agency program to develop a "rudimentary" missile defense sytem, covering the US, by 2005. Three tests, conducted in 2002, were considered successful; a June 19, 2003 test (conducted in the Pacific, using an SM-3) was considered to be a failure.

See also: National Missile Defense, Aegis class cruiser