The Ground-based Midcourse Defense (GMD) system is the United States' only operationally deployed missile defense program capable of defending the entire U.S. homeland (including Alaska and Hawaii) against long-range ballistic missile attacks. GMD is designed to detect, intercept and destroy long-range ballistic missiles during their midcourse phase of flight. The system provides early detection and tracking during the boost and midcourse phase, as well as target discrimination, precision intercept and destruction of the target through force of collision. GMD is an integral element of the U.S. Missile Defense Agency's layered ballistic missile defense architecture. As prime contractor, Boeing designs, produces, integrates, tests and sustains all GMD components deployed across 15 time zones.