Not all proposals for deploying a national missile defense live up to their name. Many are for "international" missile defense systems that would also defend U.S. allies and "friends," even though they are wealthy enough to build their own missile defenses. For example, some policymakers and analysts on both the left and the right advocate sea-based missile defense as a substitute for the Clinton administration's limited land-based system, which is designed to protect only the territory of the United States. Conservatives would like to build a more comprehensive, layered defense consisting of sea- and space-based weapons or land-, sea-, and space-based weapons. George W. Bush, the presumptive Republican presidential nominee, is clear that he wants a comprehensive defense to defend U.S. allies and seems to favor the latter approach.
Any defense expenditure--including spending on missile defense--must be commensurate with the threat. More robust missile defenses are not justified by the limited threat. Also, sinking large amounts of funds into more comprehensive missile defenses--when even the Clinton administration's limited system might fail because of technical risk or lack of adequate testing--is questionable.
The main objective of conservatives in supporting more robust missile defense systems does not seem to be defense of the U.S. homeland. Instead, their aim seems to be to create a stronger shield behind which the United States can move against potential regional adversaries possessing weapons of mass destruction and long-range missiles to deliver them. The reasoning is that, if such adversaries cannot threaten the United States or its allies with catastrophic retaliation, U.S. policymakers will feel more confident in intervening militarily. But because any missile defense system cannot guarantee that all incoming warheads will be destroyed, that reasoning is a dangerous illusion that could actually undermine U.S. security. Thus, development of a missile shield should be confined to the more limited land-based system that the Clinton administration has proposed.