100th Missile Defense Brigade (Ground-based Midcourse Defense), known as 100th MDB (GMD), is a multi-component Army national guard brigade headquartered at Schriever Air Force Base, Colorado. It has component formations located in Fort Greely, Alaska, and Vandenberg Air Force Base, California, manned by national guardsmen of the 49th Missile Defense Battalion, and 100th MDB, Detachment 1, in Alaska and California, respectively, on a round-the-clock 24/7 basis. 100th MDB (GMD) is part of the United States Army Space and Missile Defense Command.