During the cold war, nuclear strategic doctrine was riven by a fundamental contradiction. Governments thought it sensible to threaten nuclear war--the better to "deter" a foe from doing something unwanted--yet it obviously made no sense actually to wage nuclear war, for this led to the famous "mutual assured destruction." But if carrying out the threats was senseless, then how could it be frightening? What use were they? Wouldn't the foe, supposing that no country would be demented enough to "assure" its own destruction, disbelieve the threats and do what it pleased in spite of them?

The high strategists of nuclear defense scratched their heads and came up with answers. One was to take technical and other steps that deliberately put your nation on what the strategist Thomas Schelling called a "slippery slope." That is, if you visibly arranged to make yourself a little bit out of control, the foe would no longer be able to imagine that you might desist from nuclear war in a last-minute fit of sanity. They'd think that you might plunge into the abyss in spite of yourself. And so they would fear you, as hoped. (The inexorable mobilization schedules of World War I acted thus, once diplomacy had broken down, to assure the start of a war that was in no one's interest.) Another solution, also pioneered by Schelling, among others, was the deliberate cultivation of a reputation of irrationality. Schelling called this policy the "rationality of irrationality." In this policy, the foe would believe in your self-destructive threats not because it thought you might slip on a banana peel, so to speak, at the brink but because it believed you just might be lunatic enough to go over the edge deliberately.

Richard Nixon was one practitioner of this strategy. When he came to office, he planned to end the Vietnam War on terms favorable to the United States by frightening North Vietnam and the Soviet Union into compliance. He hoped, by persuading them that he was just a little bit off his rocker, to scare them into submission. He called the strategy the "madman theory." In practice, however, it failed. The Russians and the North Vietnamese ignored the threat and went on to win the war.

When the cold war ended, most people probably bid an unfond farewell to these blood-freezing paradoxes, along with the Soviet-American nuclear arms race that had given rise to them. They may be surprised, therefore, to find them returning in the new context of what many call the second nuclear age (the first having consisted of the cold war). Recently, the United States--the world's "only superpower," or "hyperpower," as the French say--has found itself in a nuclear stalemate with tiny, poverty-stricken but (probably) nuclear-armed North Korea. North Korea has rediscovered the madman theory with a vengeance. It cannot be in the interest of North Korea, to state what is sickeningly obvious, to get into a nuclear war with the United States. At the moment, North Korea is incapable of striking American soil with a nuclear-armed missile. At the most, it can fire a few nuclear weapons at South Korea or Japan. The United States, of course, has more than 10,000 fully deliverable nuclear bombs. And yet North Korea's Dear Leader, Kim Jong Il, has been bellowing nuclear destruction at the United States. His country possesses, his spokesmen have said, a "powerful deterrent" that can turn South Korea--and the American bases in South Korea--into a "sea of fire" (a phrase the North Koreans seem almost to have copyrighted). Just recently, North Korea declared its promise to South Korea not to build nuclear arms "nullified"--owing to America's threats to destroy the regime.

Kim is well suited to the role of madman. This leader (with his accidentally fashionable spiky, two-inch-tall hair) of a regime that has starved millions of its people and is perhaps the most regimented on earth, does not have to strain to convince the world that he might be capable of irrational acts. And yet it's also true that those acts display--shades of Thomas Schelling--the "rationality of irrationality" more clearly than anyone has done before, since the United States has indeed been deterred (at least so far) by his threats.

Yet there is no need to go halfway around the world to find the resurrection of the madman theory. We only have to look at our own government. The Bush Administration has been puzzling again over the paradox that a threat is no good if it appears crazy to carry it out. Linton Brooks, the acting administrator for the National Nuclear Security Administration, has said to the New York Times, "We need to make sure our weapons will in fact be seen by other countries as a deterrent. One element of that is usability. If nobody believes there is any circumstance where you will use the weapon, it is not a deterrent." Therefore the Administration has proposed that a legislative ban established in 1993 against low-yield nuclear weapons (less than five kilotons of explosive power) be rescinded, and the Senate Armed Services Committee, voting largely on party lines, has just concurred. The change is in keeping with a broader revival of nuclear threats by the Administration, which also revived the production of the plutonium pits that are at the core of nuclear bombs, which wants to shorten the time necessary to resume testing and which seeks funds to study a new nuclear weapon called the Robust Nuclear Earth Penetrator. (It's hard to know when this Administration is merely tone-deaf to the overtones of its jargon and when it is deliberately trying to provoke its opposition with outrageous nomenclature.)

However, the trouble, once again, is that if you establish usability, you may get use. And is the first use of nuclear weapons since Nagasaki what the United States now seeks? And can the United States succeed in persuading other nations not to acquire nuclear weapons when it insists not only on possessing them but on using them, and what is more, using them first? Carl Levin, the ranking Democrat on the Senate Armed Services Committee, comments, "This just undermines our whole argument. We're driving recklessly down a road that we're telling other people not to walk down." And what if, as you cultivate your own new version of the madman theory, your adversary does the same, as Kim Jong Il now is doing? One madman leaves the hope that the adversary may be sane. Two could push us all into the sea of fire.

• Get The Nation at home (and online!) for 75 cents a week!
• If you like this article, consider making a donation to The Nation.