With Washington embroiled in battles over the president's proposed Department of Homeland Security and corporate America's scandalous misdeeds, it caused hardly a blip on the capital's radar screen when the Anti-Ballistic Missile (ABM) treaty expired last month. There were a few celebrations among the treaty's critics, but its supporters were remarkably silent.

The Russian government pragmatically realized that fighting for the ABM Treaty was a losing battle, so it decided instead to extract whatever advantages it could in return for its acquiescence. As the Russian opposition collapsed, so, more or less, did that of European politicians and Democrats, who had predicted dire consequences because of the Bush administration's actions.

But the extraordinary lack of controversy belies the importance of June 13. The United States is now freed from any constraints on efforts to build an effective missile defense. Such constraints, enshrined in the ABM Treaty, had been accepted by the Clinton administration as unending. During the 1990s, this policy prevented the United States from protecting itself against the growing threat of ballistic missile proliferation among the rogue nations of the world-and non-rogue nations too, for that matter.

No one who attended a recent conference on the issue, organized by The Heritage Foundation and the McCormick Tribune Foundation, could come away without a sense of the tremendous number of threats that could face the United States. Fortunately, we now have the possibility for a measure of protection-if President Bush chooses to pursue it.

Conference speakers revealed in disturbing detail how far the proliferation of missile technology has gotten out of hand. More and more advanced missile technology is spreading from "Axis of Evil" countries, primarily North Korea, whose three-stage Taepo Dong intercontinental ballistic missile (ICBM) will be able to reach parts of the United States. Another equally troubling and even more difficult threat to anticipate is represented by cruise missiles or unmanned armed vehicles (UAVs), which are widespread and which could fall into terrorist hands. Any one of these hitting the U.S. homeland armed with a nuclear, biological or chemical warhead would be horrendous. By one estimate, a nuclear surface burst hitting St. Louis would kill almost 9,000 people on impact and another 51,000 from radiation.

Worrisome as the number of nightmare scenarios is, it should be obvious that we must protect the United States and its allies against the dangers we can counter. While low-flying cruise missiles will be difficult to intercept, the ballistic missile threat is one we can handle. The shame is that we are looking at a wasted decade in the 1990s where the Reagan/Bush missile defense programs were abandoned in favor of conventional arms control.

The missile-defense program that was finally started in the late 1990s, and inherited by the second Bush administration, is a limited combination of sea- and land-based interceptors. It will be far from adequate, according to the experts meeting at the McCormick Foundation's Cantigny estate outside Chicago. This, despite the fact that the Bush administration is proposing to increase spending on research, development and testing by 70 percent ($30 billion was spent between 1993 and 2000).

A big difference between the "hand-me-down" Clinton Ballistic Missile Defense, the program inherited by the current Bush administration and the missile-defense systems pursued by Ronald Reagan and the first President Bush is that the Clinton program was planned to be deployed in compliance with the ABM Treaty; the others were not. The Clinton BMD plan was not designed to defend against Russia's nuclear arsenal; the Reagan/Bush programs were designed to withstand the heaviest possible attacks.

An effective system of missile defense has to include space-based interceptors, which is the only comprehensive way to shoot down missiles in their boost phase as well as in mid-flight. That means going back to the concepts of the Reagan Strategic Defense Initiative and the first Bush administration's "brilliant pebbles" blueprint. That idea still causes much heartburn among the Russians and Chinese-not to mention various domestic opponents of the "militarization of space."

But space already was militarized when the Soviets tested their first ICBM a half-century ago. By placing our defensive weapons there, we would only be following their lead.

Helle Daleis deputy director of the Davis Institute for International Studies at The Heritage Foundation, a Washington-based public policy research institute.