When you lose a war, as the United States did in Vietnam, there is nothing you can do about the mistreatment of your POWs. When you win a war, you are not nearly so helpless.

The only Confederate official executed by the Union after the Civil War was Henry Wirz, the commandant of Andersonville Prison where thousands of captured Union soldiers died.Nearly a century later at Nuremberg, the United States gained more experience in the hanging of war criminals. But not having had a victory in a major war in almost half a century, we are out of practice.

We are now engaged in a war we are going to win. We should therefore make it very clear to those who are going to lose that if they commit war crimes we shall attempt to hang them even after surrender.

We should make clear that mistreatment of POWs is one such war crime. Using chemical or biological weapons is another. Either act will be sufficient to cause the United States to pursue those responsible.

Our intent is to kill them while the war is on (the blanket prohibition against assassinating foreign leaders being a measure not even Congress can take seriously anymore) and to try them when it is over.

This war began with one declared aim: the liberation of Kuwait. We now have another: the prosecution of war criminals. But the list should not stop there.

There will, of course, be legalists who will howl at any suggestion that we transgress the mandate of United Nations or congressional resolutions. But all these are pre-war mandates. War changes everything.

One might let an aggressor get away with only giving up his booty if he does it in a way that spares the world a war. (In Geneva a week before the war, Secretary Baker offered Tariq Aziz exactly that.)

But if he does it in a way that doesn't spare the world a war, then those forced to go to war are entitled to demand far more.

Aggression is one thing. Bringing on a war is another. Having forced us to expend blood and treasure, Saddam cannot be permitted a retreat to the sanctuary of the status quo ante.

From the beginning, the real issue, the casus belli, in the Persian Gulf was not so much Kuwait as Iraq. The liberation of Kuwait is certainly the essential step in stopping Saddam, and the only one around which we could gather an international consensus.

But the real object of our policy is Iraq: not destroying Iraq, but reducing it by decimating its vast warmaking machine.

During the war, there is no need to announce this goal. The decimation proceeds as we speak. But it is always possible that either a coup or a bullet or yet another Saddam change of course could lead to an Iraqi offer of a cease-fire and an evacuation of Kuwait.

Too late. Evacuation is no longer nearly enough. What, then, is?

In World War II, it was not until 1943 in Casablanca that the allies fixed on their war aim: unconditional surrender. It was the only way to eradicate Hitlerism from the globe. It is the only way to eliminate Saddamism.

Saddamism, as the critics endlessly repeat, is not quite Hitlerism: The evil is more instrumental, the cruelty is less systematic, its power is as yet regional not global. Yet Saddam's performance since Jan. 16 should give the skeptics pause.

His mistreatment of POWs, his unprovoked missile attacks on cities, his threats once again to use poison gas, his turning captives into human shields is rather convincing evidence that Saddam represents barbarism unusual even by 20th century standards.

And barbarism on the march is not barbarism to be accommodated. Our goal today, as in 1943, should be unconditional surrender.

That does not mean the establishment of a MacArthur regency in Baghdad. Beyond eliminating Saddam, Iraq's internal politics are not our concern. They are, moreover, far beyond our control.

What then do we mean by unconditional surrender? It means these measures after the war:

The systematic on-site inspection of all of Iraq's military industrial complex.

The total elimination of all of Iraq's chemical, biological and nuclear potential.

The reduction of its army and conventional weaponry down to levels commensurate with that of its neighbors. (Lower than that and we have to occupy Iraq in order to save it from its neighbors. We have had enough Middle Eastern ironies. We can spare ourselves this one.)

These measures are to come after the liberation of Kuwait, and before the war crimes trials.