The Iraqi bomb is a red herring. President Bush's Thanksgiving Day invocation of an imminent Iraqi nuclear threat to justify war in the Persian Gulf misreads history. Expert estimates put Iraqi acquisition of a limited nuclear arsenal at least 10 years away.

But even if Iraq were soon to assemble the one crude atomic bomb that Defense Secretary Dick Cheney described, the experience of one nation after another across 45 years of postwar history has demonstrated that acquiring such weapons in a nuclear-armed world is inescapably self-deterring.Nations have sought to acquire nuclear weapons because an enemy has acquired them or because they feared it would do so, and because they wished to command increased international respect. Both motives drove the U.S. effort during World War II and the Soviets' effort during the postwar years; both motives probably drive the Iraqi effort today.

When a national leadership contemplates its shining new nuclear arsenal, however, it soon learns it has made itself more vulnerable rather than less. The only nuclear weapons ever exploded in war were exploded against a non-nuclear opponent. Attacking a nuclear power or a nuclear power's client invites nuclear retaliation.

A corollary unwelcome lesson that arriviste nuclear powers learn is that nuclear weapons are useless militarily, precisely because using them would trigger nuclear retaliation.

Significantly, nations have pursued nuclear deterrence in defense against historic enemies. The United States and the Soviet Union armed against each other; China against all; India to deter China as well as Pakistan; Pakistan to deter India.

The Iraqi effort follows that norm, paired in this case with Israel.

Indeed, the one nation an Iraqi bomb might seriously discomfit is Israel, which is why Israel pre-emptively destroyed Iraq's Osirak nuclear reactor in 1981.

Not that Saddam Hussein or his successors would be likely to attack Israel with nuclear weapons if they had them. Such an attack would be self-evidently suicidal, given Israel's formidable nuclear arsenal, estimated to contain between 100 and 200 boosted fission weapons.

Rather, an Iraqi nuclear capability would threaten Israel by deterring it from nuclear reprisal against conventional attack, the mainstay of its present strategy for survival in the volatile Middle East. At the same time, Iraq would continue to be deterred from attacking Israel.

No doubt Israel would prefer to remain the only local nuclear power in the Middle East. More than four decades of hard experience taught the United States and the Soviet Union that conventional war under the shadow of nuclear deterrence leads inevitably to stalemate because neither side dares to push the other side far enough to provoke nuclear attack.

In the short run that stalemate encouraged the status quo - the division of Europe, two Koreas, the balance of power in the Middle East.

But arms races are expensive, times change, populations become restive and eventually such pressures must drive the stalemated nations to the bargaining table, forcing them to resolve their disputes by negotiation rather than militarily.

(Richard Rhodes is author of "The Making of the Atomic Bomb.")