The Missile Defense Agency (MDA) is the section of the United States government's Department of Defense responsible for developing a layered defense against ballistic missiles. The agency has its origins in the Strategic Defense Initiative, which was established in 1983 and was headed by Lt. General James Alan Abrahamson. It was renamed the Ballistic Missile Defense Organization in 1993, and then renamed the Missile Defense Agency in 2002. See National Missile Defense for the history of DoD missile defense programs.