Charles V. Pena is a senior defense policy analyst at the Cato Institute.

President Bush and Russian President Putin (whom Bush now refers to as his “new friend”) are scheduled to meet at a summit in Washington, D.C. on Nov. 13. Likely to be at the top of the agenda is missile defense and the Anti Ballistic Missile (ABM) Treaty. As the summit approaches, it appears that the United States and Russia will agree to allow extensive missile defense testing without abandoning the treaty (although this continues to be a long-term goal of the Bush administration).

However, there is one fundamental question that still lingers and that has not received much attention in the public square: What is the exact scope and nature of a missile defense system?

The Bush administration has been intentionally vague about the exact details and system architecture. According to the Ballistic Missile Defense Organization (BMDO), its objective is to “develop the capability to defend the forces and territories of the United States, its allies, and friends against all classes of ballistic missile threats.” Furthermore, the secretary of defense has directed that the program focus “on missile defense as a single integrated BMD [ballistic missile defense] system, no longer differentiating between theater and national missile defense.”

It would seem, then, that national missile defense has quietly become global international missile defense, designed not just to protect the United States (although missile defense is portrayed to the American public as defending the United States), but also allies and friends around the world. Indeed, the Bush administration plan seems no different than the “from anywhere to anywhere” threat rationale used for the GPALS (global protection against limited strikes) system proposed by the previous Bush administration. This should come as no surprise because many of the top thinkers and decision-makers in the current administration are holdovers from the elder Bush’s tenure.

But why should the United States shoulder the burden of a global missile defense system (likely to cost well in excess of $100 billion, if not several hundred billion dollars) when many of the friends and allies that such a system would protect are wealthy enough to pay for their own missile defense, already spend too little on their own defense, and already benefit from U.S. security guarantees?

Furthermore, such a system mimics the overextended U.S. defense perimeter, which is built on the misperception that vital U.S. national security interests require defending every region of the globe and responding to every crisis in those many regions. The belief is that a global missile defense system would create a shield that would give the United States freedom of action to operate with relative impunity throughout the world. But if policymakers feel more secure, they may also feel more emboldened to engage in reckless overseas military adventures, which could actually undermine U.S. national security.

If the United States is going to build a new strategic framework with Russia and eventually scrap the ABM Treaty (although Russia still considers the treaty central to nuclear stability), it should do so to provide real national security for the U.S. homeland and not to be the world’s policeman. Advocates of missile defense are quick to paint a “doom and gloom” picture that America and Americans are defenseless against attacks from ballistic missiles. Why then are we pursuing a system that will defend the world and will be significantly more expensive than a system designed to defend the United States? Seems a little like “bait and switch” tactics.

The single most important function of the U.S. government is to protect the American people. To the extent that a truly national missile defense system is technically and operationally feasible and fiscally affordable, the U.S. government should strive to develop and deploy such a system. But any defense expenditure—including spending on missile defense—must be commensurate to the threat. The potential rogue state threat is limited. Terrorists armed with ballistic missiles are an even more limited and more remote threat (and terrorists are highly unlikely to use ballistic missiles because they provide an immediate and known “return address” for retaliation).

It is disingenuous to say “America is defenseless” as a rationale to gain public support for missile defense, but then to pursue an exorbitantly expensive global system to defend U.S. friends and allies overseas. Instead, the United States should develop and deploy a limited and more affordable land-based national missile defense designed to protect the U.S. homeland.