The whims of dictators can change history. Adolf Hitler, favoring research that could have an immediate battlefield effect, slighted Germany's program to develop an atomic bomb. The weapon that could have pulverized Britain was never developed. Similarly, Saddam Hussein invaded Kuwait and threatened Saudi Arabia about five years too soon. By 1995, he might have joined the nuclear club.

The prospect of Iraq with nuclear weapons and the missiles to deliver them is not a pleasant one. In recent days, Iraq was reported to have moved Scud missiles into Kuwait. These missiles have the range to hit key Saudi cities and air bases. But the Iraqis don't yet have the technical expertise to aim their missiles with precision and, according to Western intelligence, don't yet know how to arm them with poison gas. Atomic weapons, though, are much more forgiving of sloppy marksmanship.

The world is entering a dangerous era -- nuclear weapons in the hands of unstable regimes and, in some cases, unstable leaders. Israeli intelligence reckons Iraq is just five to seven years from developing atomic weapons and the requisite missile-delivery system. India has joined the nuclear club, and Pakistan is knocking on the door.

Libya undoubtedly has tried to steal either a bomb or the technology to make one, and of course the Soviet Union, the United States, Britain, China and France retain their nuclear arsenals. Had they the desire, there's no doubt Germany, Japan and, maybe, South Korea could produce a bomb in very little time. Israel almost certainly has atomic, if not hydrogen, weapons.

Maybe in principle no nation should have nuclear weapons -- and maybe some day we can all afford such a principle. In the meantime, the question is what to do about nuclear weapons in the arsenals of regimes like Iraq. Unlike Israel's (or Britain's, etc.) those weapons might be used offensively and not defensively or merely to deter. Think of Moammar Gadhafi with atomic bombs at his disposal.

Iraq's invasion of Kuwait, even if no wider war erupts, is one of those watershed developments after which nothing will ever be the same. In the United States, it marked the absolute end of the post-Vietnam era, when, almost predictably, the American left would recoil from any use of force for any purpose. That is now behind us. Iraq's aggression also smashed the facade of Arab unity -- all that business about one Arab nation -- and made the Saudis, among others, own up to their dependence on American power and, even, their friendship with the United States.

But, for me, maybe the most important consequence of the Gulf crisis has been the revival of the United Nations. It is important because only international organizations will be able to deal with the growing menace of nuclear proliferation. The present crisis is in the Persian Gulf. But in the shadow of the larger headlines are smaller ones about Pakistan and India, once again growling at one another, once again exchanging shots across the border. At least one of these nations have nuclear capabilities -- and so, for that matter, may South Africa.

President Bush has been masterful in assembling an anti-Iraq coalition -- in effect isolating Iraq so that its only ally seems to be the PLO. And again in Kennebunkport on Monday he struck just the right note in affirming that it's the international community, not just the United States, that has a problem with Saddam. He cannot say that too often. By implication, he has abandoned the Reagan administration's antipathy for the United Nations and the World Court.

Now is a stressful time in Washington and other world capitals. War looms. But it's also a propitious time to focus attention on the spread of nuclear and chemical weapons. Not only should the United Nations be given some teeth to deal with this problem, but nations such as Germany and Switzerland have to be reminded once again that some of their firms have turned Third World dictators into first-class menaces. The exportation of chemical, biological and nuclear death has to stop.