An especially odd aspect of the Bush administration’s drive for military action against Iraq is the underlying assumption that the United States cannot deter Saddam Hussein if he acquires nuclear weapons. That is a startling departure from a core feature of U.S. security strategy since the end of World War II. U.S. officials have invariably believed that the vast U.S. strategic arsenal would ultimately deter any would-be aggressor — even a nuclear-capable one.

Over the years, the United States has deterred the likes of Joseph Stalin, Nikita Khrushchev, Leonid Brezhnev and Mao Zedong. None of those leaders seriously contemplated attacking the United States or even key U.S. allies. And the reason for their restraint was quite simple: They knew that such an attack would mean their own annihilation.

Why, then, do Bush administration officials apparently assume that Saddam Hussein is undeterrable? It cannot be that Saddam is more brutal than America’s previous adversaries. Khrushchev and Brezhnev were equally thuggish, and as a colleague of mine has noted, Mao and Stalin were the gold and silver medalists in the 20th century’s genocide Olympics. Nor can a credible case be made that Saddam is more erratic and unpredictable than the tyrants the United States deterred in the past. Stalin gave paranoia a bad name, and Mao was the architect of China’s utterly bizarre cultural revolution in the late 1960s and early 1970s — at the very time that China was acquiring a nuclear weapons capability.

The notion of a direct Iraqi attack on the United States is credible only if one assumes that Saddam Hussein is suicidal. Yet he has shown no signs of that trait during a dictatorship of nearly three decades. The notion that he might pass along a weapon of mass destruction to al Qaeda or another terrorist group to use against the United States is only barely more plausible. Saddam knows that his name would be at the top of a short list of suspects if such a weapon ever went off in the United States, and that American leaders would not be inclined to require proof beyond a reasonable doubt before ordering a devastating counterstrike.

A man who sleeps in a different location each night to preserve his life does not seem the type to throw that life away by attacking (directly or indirectly) the most powerful nation on earth. Saddam may be a thug, but he is a rational thug, and he understands that sponsoring such an attack would be signing his death warrant.

When pressed, many advocates of military action against Iraq concede that an Iraqi attack on the United States is improbable, but their fallback position is that Saddam in possession of nuclear weapons would pose a mortal threat to other countries in the region. That concern has some validity, although the history of other new nuclear weapons states suggests that the possession of such weapons does not translate readily into regional dominance. A nuclear-armed China was not even able to prevail against Vietnam in 1979, and a nuclear-armed India has not been able to intimidate Pakistan on the Kashmir issue.

Iraq would likely find the same limitation in its region. The most feared scenario — an assault on Israel — is actually the least likely. Such an attack would be nearly as suicidal as an attack on America, since Israel has 200 to 300 nuclear weapons of its own.

An Iraqi move against other neighbors that do not possess weapons of mass destruction is more plausible. But if the Bush administration concedes that the United States might not be able to deter an attack on allies or clients in that region, there are important implications for America’s security commitments in other regions. Just last year, the president gave a firm pledge to do “whatever is necessary” to protect Taiwan from a Chinese attack. And the United States is poised to give security guarantees to an assortment of new NATO members.

Bush administration officials cannot have it both ways. If it is difficult to deter tiny Iraq from coercing its neighbors in the Middle East, it would surely be more difficult to deter a much larger and more powerful China from taking action against Taiwan. Similarly, can U.S. officials be certain that Washington would be able to deter a post-Putin Russia from threatening Estonia and other small Baltic neighbors?

The Bush administration needs to make up its mind. If it believes in deterrence, its policy toward Iraq makes no sense. If it no longer believes in deterrence, U.S. policy in other parts of the world makes no sense.