National missile defense history The idea of a national missile defense system has been around since the 1950s. It is an indication of the difficulty involved in perfecting a missile defense system that there still is not a perfected system in place today. An anti-ballistic missile (ABM) system must be able to perform six separate functions in order to be effective. It must be able to detect an incoming missile or warhead with sufficient lead-time to allow it to perform the rest of its

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... . The ABM system must be able to identify that the information being received is in fact an incoming missile. The radar system or other detection devices (optical, infrared, etc) must be able to track the flight path of the incoming target. Once a missile or other weapon is launched against the target, the system must be able to guide it to its intercept point. Of course, a successful ABM system must be able to destroy the target or render it inoperable. Finally, because even one nuclear weapon can have a devastating effect, the ABM system must be able to verify that a target is engaged successfully, and if not, attack the target once again. Five of these functions are independent of the type of missile used to destroy the target. They rely on a complex and integrated system of satellites, land-or sea-based early-warning radars, and target tracking and missile guidance radars. The target can either be destroyed by actually hitting the incoming target, so-called hit-to-kill technology, or by detonating a small nuclear device nearby, which would either destroy or disable its capability. Satellites Satellites have been, and still are, an important component of missile defense architecture. They are used for early warning, target identification, and battle management. They are also the most vulnerable component of the system. Because they have to be launched into space, they must be lightweight which makes them very fragile. In addition, satellites follow very predictable orbits and can be identified easily from the ground. Although all industrial countries have refrained thus far