So, for example, having an operational Airborne Laser system and a ground based system give the sea based interceptor more timely and accurate information with which to do its job.

CENTERFORSECURITYPOLICY: 33 Minutes

Such systems include all phases of the Phased Adaptive Approach to missile defenses in Europe, the modernization of the Ground-based Midcourse Defense system, and the continued development of the two-stage Ground-Based Interceptor as a technological and strategic hedge.

CENTERFORSECURITYPOLICY: Center for Security Policy | Mapping a National Security Failure: Ratification of the New START Treaty | Page: 14

Deterrence: The first phase system should be comprised of ground and space-based sensors and interceptor systems.

CENTERFORSECURITYPOLICY: Center for Security Policy | An Assessment Of Future Requirements For US Strategic Forces And Strategic Arms Control

Interestingly, Mr. Davis has cited the importance of layered or "tiered" defense among his rationales for restarting the canceled E2I secondary interceptor for the single ground-based defense site he advocates -- despite the fact that the E2I system does not represent an independent layer.

CENTERFORSECURITYPOLICY: Center For Security Policy