The question on everyone's mind is: When will the United States start its ground offensive? A better question is: Why should the United States start a ground offensive? Given the relative impunity with which allied air forces can operate over Iraq and Kuwait, why even contemplate a ground war until the air war has exhausted itself?

The most surprising development in the Gulf war is not Saddam's headline-grabbing sideshows (made-for-TV attacks on Jews, sea birds and other hard targets). The single most surprising development is the astonishingly low allied casualty rate in the air war. American air losses after two weeks have yet to equal the number of Americans lost in three days in Grenada.

Indeed, more Americans died in one brief land skirmish on Wednesday than in two weeks in the air. What possible justification can there be for risking huge losses on the ground when such immense destruction can be delivered at virtually no cost from the air?

Air war is sanctions with teeth. (Iraq's relative resilience in the face of such a savage air campaign casts new light on the Democrats' pre-war fantasy that economic sanctions alone would bring Iraq to heel.) Iraq, perhaps the most militarized society on Earth, is seeing its military infrastructure relentlessly destroyed. It is a strategy that we can sustain almost indefinitely. Saddam cannot.

Public support for the war is now extraordinarily high. Why? Because casualties are extraordinarily low. Saddam's only hope for victory is a collapse of domestic American support for the war. That is why he orders near-suicidal cross-border attacks into Saudi Arabia. He is desperate for the ground war to begin.

Why accommodate him? Americans like their wars neat and quick. But forced to choose, they prefer neat to quick. Americans are impatient, but they are not foolish. There is no domestic pressure whatsoever to hurry the war and press ahead with a bloody ground offensive.

There are, to be sure, foreign pressures to conclude this war quickly. Time is not completely on the allied side. First, the coalition is fragile. With every passing day, pro-Saddam Islamic sentiment is aroused from Pakistan to North Africa. More important, anti-allied, anti-American pressure grows in Egypt and Turkey, the loss of either of which to the coalition would be a severe blow to the war effort.

Soviet support for the war, already wavering, could entirely dissolve with time. A Soviet defection could mean, at the extreme, Soviet resupply of Iraq. Less extreme but very damaging still would be Soviet agitation for a cease-fire and negotiations. Egypt, Turkey, Syria and other Moslem countries give the war cover in the Islamic world. Soviet support gives the war cover on the left and among Third World radicals. The longer the war, the more spotty the cover.

There are further uncertainties. Iranian and Jordanian neutrality will be hard to sustain indefinitely. So will Syrian support for the coalition. Nonetheless, these pressures do not justify the enormous, potentially fatal risk of a ground war. These are diplomatic problems. It is tempting to try to preempt them militarily. But it is better to keep our nerve and deal with them diplomatically when they arise. We dealt successfully with Iraq's attempt to fracture the coalition with Scud attacks on Israel. We can deal with other threats to the coalition.

The other problem with a long war is that with every passing day Saddam's stature grows in the Arab world. Given the quick Arab collapse in the Six Day War and other humiliating defeats, the longer Saddam holds out against a coalition of Great Powers the more he becomes a hero and a rallying point for Islamic anti-Americanism.

The answer to that problem is simple: victory. If, in the end, Saddam is decisively defeated and his regime destroyed, the length of his holding out will matter only to historians and romantics. If Saddam survives, the length of the war will matter. If he doesn't, it won't.

There are thus only two reasons to hurry: concern for the coalition and concern about enhancing Saddam. And both can be dealt with, one by diplomacy, the other by victory.

There is, however, one overriding reason not to hurry. This war has two goals. The immediate goal is to save the Middle East from Saddam. The other goal is to spare the world future Saddams by making of him an example.

If America wins the Gulf war with low casualties, then America's threat to repeat the experience will be a highly believable and therefore effective deterrent to future Saddams. If, however, this war ends with enormous American losses, the American people will say, never again. Such a win, far from deterring future aggressors, will be self-deterring for America. It will guarantee that in winning the first battle of the new world order, we have lost the war.

The time to contemplate a ground war is when the air war is doing nothing more than making the rubble bounce. To move earlier than that is to put at risk not just American lives but America's very purpose in taking up this fight.