The word "meltdown" came naturally to the lips last week, referring to the collapse of financial markets. But what about a real meltdown? The word came into popular usage to describe the melting of fuel rods in a nuclear reactor, a result of out-of-control overheating, leading to a dangerous release of radiation. But before that, meltdown defined not the accident of a power plant but the purpose of a nuclear bomb - the liquefaction through intense heat of metal, glass, and everything else caught in an atomic blast. Meltdown is the point.

Last week's financial metaphor was also last week's all but ignored real problem, as America was encouraged to take a large step in the direction of the ultimate meltdown of nuclear war. Over the signatures of Secretary of Defense Robert M. Gates and Secretary of Energy Samuel W. Bodman, the government released the statement "National Security and Nuclear Weapons in the 21st Century." In brief, the two officials argue that the time has come for the development of a new nuclear weapon, the so-called Reliable Replacement Warhead. Because "nuclear weapons remain an essential and enduring element" of American military strategy, the aging arsenal of several thousand deployed nukes (and many more "stored") must be replaced.

Gates and Bodman grant that an eventual reduction of the nuclear force, as well as ongoing nonproliferation efforts, remain desirable goals, and that the RRW will help achieve both, but what they propose runs absolutely in the other direction.

Obviously, the Bush administration will not succeed in getting a new nuclear weapon approved by Congress. What Gates and Bodman are doing here, at the behest of the diehard nuclear establishment, is putting an item at the very top of the next president's agenda.

For 20 years, the United States has been ambivalent about its nuclear arsenal. That indecision was enshrined in the Clinton administration's policy of "lead and hedge," the idea that America would lead the post-Cold War world in ongoing reductions of nuclear weapons, aiming at the ultimate abolition called for by the Nuclear Nonproliferation Treaty, even while maintaining a sizable nuclear force, both deployed and stored, as a hedge against the re-emergence of some Cold War-style threat. The policy was a deadly contradiction: The hedge made US leadership on meaningful reduction impossible.

The result is clearly described in the Gates-Bodman document: Nuclear nations today are feeling pressed to renew and expand their arsenals (seeking hedges of their own), and nonnuclear states, especially Iran, are moving toward acquisition. The predictable results of the Clinton hedge, that is, are now being used to justify the abandonment of the goal of reduction toward elimination. Nukes forever.

Gates-Bodman are correct to want this issue on top of the next administration's agenda, and they are correct in their implicit argument that the time has come for US ambivalence to end. But they are dead wrong in how to end it.

The world was given a rare second chance on the nuclear horror when the unlikely Ronald Reagan joined Mikhail Gorbachev in proposing abolition. That second chance is not quite gone. What has to happen now is clear. In the near term, no new weapons. The nuclear arsenal must quickly be reduced to minimal levels (dozens or hundreds, not thousands). Against Gates-Bodman, who see nuclear weapons as deterring against conventional assaults (nukes as just another weapon), the United States must reaffirm that nukes deter against nukes, period. This weapon is in a class by itself, which requires the long-overdue adoption of "no first use." And against Gates-Bodman, who imagine, if deterrence fails, an actual use of nuclear weapons to "defeat" an enemy, the United States must return to the Cold War recognition that once nuclear war begins, all notions of victory and defeat are meaningless. That is why it is urgent, for the longer term, that Washington reaffirm the policy that began with Truman - that these weapons are to be eliminated as soon as possible.

"Meltdown" is one word that cropped up as financial markets crashed. Another was "abyss." A financial abyss is horrible to contemplate, but it is still a metaphor. The abyss threatened by nuclear weapons, alas, is real, and the last chance to avoid it is here.