The United States is currently developing the of BMD systems described in the chart below. Two basic technologies are being actively pursued today: anti-missile missiles and lasers mounted on aircraft. BMD systems also differ in the range of the missiles they are intended to defend against (short-range/theater or long-range/intercontinental), the size of the area they can protect (a point target or a wider area), and the stage of flight at which they intercept the incoming missile (boost-phase, midcourse, or terminal stage). The United States is also conducting research on more advanced space-based antimissile systems.

Proposed Ballistic Missile Defense Systems

The United States has no systems today that can be deployed to defend against ICBMs. Two systems deployed today, the Patriot and Aegis-based, have some capability to defend against theater ballistic missiles. In mid-December 2001, President Bush announced that the United States would abandon the Navy Area Defense theater missile defense system, citing cost overruns.

Most of the BMD systems currently under development use a kinetic kill vehicle to destroy the incoming missile or its warhead. The payload of the defensive missile smashes into the incoming missile warhead at very high speed to destroy it. The exception is the airborne laser, which would use a laser beam to destroy an enemy missile shortly after launch, during its boost phase.

President Bush hopes to use a number of these systems together to provide a layered defense of the United States against ICBM attack. The BMD system that is likely to be ready first is the Ground-Based Interceptor system. It would be deployed in Alaska to defend against the North Korean Taepodong-1 and Taepodong-2. Its earliest deployment date is 2005.