Skeptics of national missile defense often fret about whether the White House's favored system, a ground-based site in Alaska, will comply with the Anti-Ballistic Missile (ABM) treaty signed by the United States and the Soviet Union in 1972. It most likely won't. But considering what an obstacle the treaty is to U.S. national security, a little non-compliance would be welcome.

Far from being "the cornerstone of our strategic security," to quote administration officials, the ABM treaty has been forcing the United States to dumb down its missile defense programs for years. The treaty says neither party can "develop, test, or deploy ABM systems or components which are sea-based, air-based, space-based, or mobile land-based." That leaves only a fixed ground-based national missile defense, even though it will provide less effective protection than the systems prohibited by the treaty.

As a result, a missile-defense program known as Navy Theater Wide (NTW), which could be adapted relatively quickly and inexpensively into a national missile defense, is being constrained to comply with the treaty. The Pentagon has said NTW -- based on system that has been protecting U.S. ships from aircraft and cruise missiles since the 1970s -- could be upgraded easily enough to intercept longer-range ballistic missiles. But that requires testing what amounts to a sea-based national missile defense, which the treaty forbids.

An upgraded NTW would require the use of external sensors, such as the low-altitude satellite system known as Space-Based Infra-Red Sensor, to help track the launch and trajectory of incoming missiles. Such a system can help long-range missile interceptors based on Navy cruisers destroy incoming missiles relatively early in flight, when they are traveling more slowly and haven't released decoys designed to confuse interceptors.

A ground-based system, by contrast, can only shoot down missiles when they are directly overhead and traveling more than 15,000 miles per hour. A missile at this stage has already released its decoys, and - if it is hit - could possibly shower the United States with fallout from any nuclear, chemical or biological warheads onboard. External sensors aren't very helpful at this point.

A sea-based national missile defense with external sensors obviously would provide much greater protection against enemy missiles. But such a system has been ruled out by the White House because it would turn NTW into a national missile defense. In fact, the Clinton administration negotiated with Russia and three other former Soviet states in 1997 to forbid any "networking" of tracking data -- meaning that NTW can't rely on anything other than ship-based sensors.

The treaty has been used to dictate other restrictions. For example, the White House pressured the Pentagon to reduce the speed of the Aegis interceptor so that it defends a smaller area than it would otherwise be capable of protecting. Why? Because then the Russians can't accuse the United States of trying to turn NTW into a national missile-defense program, a clear violation of the treaty.

Current U.S. missile-defense policy thus creates a classic Catch-22. Critics say that missile defense requires further testing to be effective. Yet compliance with the ABM treaty prohibits the sort of testing regimen needed to field an advanced system.

The question naturally arises: Why would the United States sign such a treaty? Recall that in 1972, Americans lived in a two-superpower world, with both players armed with hundreds of long-range missiles. The ABM treaty was based on a theory of "mutual assured destruction," the idea that deliberate vulnerability to attack would keep the peace because an unprovoked first strike by either side would be answered with devastating retaliation by the other.

But the world has changed considerably over the last 28 years. The Cold War ended, the Soviet Union collapsed, and missile technology has spread to some two dozen nations, including such rogue states as North Korea and Iran. Adherence to the treaty under these circumstances is tantamount to courting suicide.

Most Americans agree. A recent poll by Zogby International shows that by a 2-to-1 margin respondents believe "our best hope for long-term defense is developing our own missile defense system and not relying on treaties." They're right. It's too bad the Clinton administration doesn't seem to be listening.

Jack Spencer is a defense policy analyst in the Davis Institute for International Studies at The Heritage Foundation.