In a speech last week at the National Defense University, President Bush argued that the United States “must move beyond the constraints” of the Anti-Ballistic Missile Treaty and implied that his administration would pursue a robust missile defense program — including land, sea, air and maybe even space-based components. The president was purposefully vague about the details of his plans for the ABM Treaty and missile defense. For example, moving beyond the constraints of the current treaty could mean renegotiating the pact or simply withdrawing from it. But Bush avoided announcing such a withdrawal in the speech.

The president’s speech was premature and will needlessly roil relations with the Europeans, the Russians and the Chinese. Bush is trying to pacify ardent advocates of missile defense on Capitol Hill and within the Republican Party who want to safeguard Ronald Reagan’s dubious Star Wars legacy. The problem is that the technology for missile defense needs to catch up with the advertisement.

The United States has spent tens of billions of dollars on missile defense research — a whopping sum as far as military R&D programs go — since Reagan first proposed the Strategic Defense Initiative in 1983. Yet the technology for even a limited land- based system has not been demonstrated. Proven technologies for sea, air and space-based systems are many years away. The Clinton administration was working on a limited land-based system because that was the technology closest to maturity.

A rush to deploy any system would lead to a system that is unlikely to work properly and would be expensive and time-consuming to fix after deployment — the situation now faced by V‑22 Osprey tilt-rotor aircraft being developed by the Marine Corps. Even if the North Korean missile threat matures faster than expected — unlikely, given North Korea’s current moratorium on missile testing — rushing development of a missile defense could actually delay the fielding of a workable system. The Bush administration should take its time evaluating the options and thoroughly test the technology so that taxpayers do not end up holding the bag.

National missile defense is the most complex weapon system ever built. “Hitting a bullet with another bullet” is difficult, especially when the bullet is going 15,000 miles per hour. Yet that daunting task may be less difficult than integrating the sensors, interceptors and battle management system and ensuring that it will not be fooled by decoy warheads. Instead of accelerating the development program and accepting additional risk to get anything — no matter how ineffective — deployed, tests that simulate a realistic operating environment should be added to ensure that the system works.

If the administration wants a system that can be deployed in the shortest possible time, it will probably find — as the Clinton administration did — that a limited land-based system is the option of choice. At present, a grandiose, layered, Star Wars-like missile defense is fantasy. To spend hundreds of billions of dollars on a system that is purportedly designed to counter only a narrow range of missile threats — that is, to defend against long-range missile attacks from rogue states — is a waste of taxpayer dollars. The system will provide no protection against more likely threats of weapons of mass destruction delivered by a bomb on a ship or aircraft or by a short-range missile fired from off the U.S. coast.

In addition, unlike a modest land-based missile defense, a robust, layered system might unduly threaten to negate the Russian and Chinese nuclear deterrents. Those nations might then keep more nuclear weapons in their arsenals than they otherwise would, deploy missiles with destabilizing multiple warheads, and increase the alert levels of their missiles. Increasing alert levels may be the most dangerous of all, especially if early warning systems are deficient. If either nation erroneously thought that a nuclear attack were underway and that its retaliatory deterrent would be annihilated by the combination of a U.S. offensive strike and defense system, it might have an incentive to launch on warning of an attack. That hair-trigger posture does not contribute to a stable nuclear balance. Furthermore, a nuclear arms race with Russia or China — caused by a robust missile defense — would be unnecessary, destabilizing and costly.

If George W. Bush is truly for constraining the growth of government and guarding the taxpayers’ wallet, he should start by applying those principles to missile defense. A limited threat deserves a limited expense of public funds to counter it.