ABSTRACT
National Missile Defence provides insurance against failure of diplomacy to stem the proliferation of long-range ballistic missiles, failure of deterrence, and ineffective conventional counterforce attacks. A defence of this size requires amending the ABM Treaty, but it would not pose a threat to Russia's strategic nuclear force unless this force drops below approximately 1,200 weapons. The effectiveness of a given NMD architecture can be estimated by determining the area of the continental United States that the system can cover, the performance of the surveillance and tracking sensor architecture, and the performance of individual interceptors. The extent to which a thin US national missile defence poses a realistic threat to the strategic retaliatory capability of Russia or China depends on the area each site can defend, the size and character of the attack, and the number and effectiveness of the interceptors. As an insurance policy against the proliferation of long-range ballistic missiles, national missile defence is probably not worth the costs.
