Quick Facts
Mobility	Ground-based midcourse defense
Targets	Intermediate- and long-range ballistic missiles
Role	Single target, midcourse phase missile defense
Status	22 GBIs deployed at Fort Greely, Alaska; 3 GBIs at Vandenberg Air Force Base, California; total of 30 GBIs should be eployed by 2010
Producer	Boeing Integrated Defense Systems

The Ground-Based Midcourse Defense (GMD)  is the layer of the U.S. Ballistic Missile Defense System (BMDS) , a missile defense umbrella intended to defend against limited attacks by intermediate- and long-range ballistic missiles. Using multiple sensors, communications and fire control systems, and Ground-Based Interceptors, GMD is capable of detecting and tracking intermediate- and long-range ballistic missiles in the boost phase of their flight, and destroy them during the midcourse phase of flight through “hit-to-kill” technology. Sensors provide post-attack kill assessment in cooperation with the Sea-Based X-Band Radar.

Ground-Based Midcourse Defense is composed of three main components; Ground-Based Interceptors, radar infrastructure and BMC2 systems. Operational control and execution is provided by the U.S. Army with support functions provided by the U.S. Air Force. A total of 30 are planned for deployment at Fort Greely, Alaska and Vandenberg Air Force Base, California by 2010. In addition, Ground-based Midcourse Defense fire control centers have been established in Colorado and Alaska.

Given its current deployment status, GMD provides high confidence coverage over areas including Hawaii, Alaska, and the Western to Midwestern U.S. However, extended geographical distances from the sites lowers confidence in the system's ability to protect the U.S. Southeastern and Eastern borders from long-range and intercontinental ballistic missile threats.