The exhilarating success of the allies' ground assault in the war has left almost everyone amazed. The Iraqi aggressors, battered by weeks of aerial attack, were staggering home in droves. Forces of the United States and its allies, aided by shrewd strategy, were churning across the sand faster than anyone had thought possible. A briefly fought but convincing victory, for which the allies had hoped, suddenly seemed near at hand.

Throughout these confusing days, President Bush has looked impressively decisive, and never less so than on the ground war's third day, when he bluntly rejected Iraqi leader Saddam Hussein's sleazy appeal to be let off the hook and scamper home. Bush has seen from the start that for the allies' effort to have lasting meaning, Saddam and his fighting power must be permanently weakened. Letting Saddam bring his tanks and howitzers home from Kuwait in stately procession, after the violence his soldiers wreaked on Kuwait and its people, would have been grotesque.As the Iraqi menace crumbled, and as allied forces swarmed in to liberate a sadly ravaged Kuwait City, it was notable that Arab detachments were up front with those from the United States, Britain and France. This was symbolic, but it also was something more: It showed that someone has a keen eye to the region's future.

The Arab presence was crucial to the coalition's credibility in the Islamic world, and Arabs - not Westerners - can expect to play the leading role in shaping their region's postwar future. It's well that they start now.

Far murkier, as attention starts to swing to the war's aftermath, is the likely role of the Soviet Union. President Mikhail Gorbachev, working his own ample agenda, did not help coalition efforts by interjecting unworkable peace plans and then, through the United Nations Security Council, urging a cease-fire. Letting up on the pressure would have let Saddam and his forces regroup, still more or less intact. This would have appalled his Arab neighbors, most of whom by now hope fervently for his extinction.

The Gorbachev gambit appears to have done no great harm, as things turned out, and it is worth noting that the Soviets did not make heavy weather of their intervention. Once America, Britain and France firmly said nothing doing, the Soviets in effect shrugged, said "no hard feelings," and quieted down.

The United Nations, for its part, should be wasting no time in establishing a multinational force - well-armed, well-financed - to help keep the peace in Kuwait and deter any neighbors from a temptation to fish in troubled waters. For obvious reasons, Arab units should form the core of such a force.

The United Nations, furthermore, should be organizing to take the lead in setting up a war crimes tribunal to deal with the atrocities committed by Iraq against Kuwait and Kuwaitis. The war to free Kuwait was fought under U.N. auspices; the same commitment to justice would be best sustained by seeing that Iraqi war crimes do not go unpunished.

These few days in February 1991 will prove to be pivot points in the history of the Middle East. Much appears to have been gained, apart from the signal achievement of driving the Iraqi dictator out of Kuwait.

The allies' stunning success, far from poisoning the Arab world against the West, may convince many Arabs that we are serious about rebuking aggression and even about righting old wrongs. The coalition's determination also shows that many nations are quite fed up with terrorists and with those regimes (i.e., Iraq) that give them aid and comfort.

The sweeping victory, by shuffling the Middle East's political deck, may even create new opportunities for a deal between Palestinians and Israelis. Yasser Arafat, who foolishly banked on Saddam to be his champion, has lost whatever feeble standing he enjoyed. If more moderate Palestinian voices now emerge to be heard (and if Israel can be persuaded to see that this is a rare window of opportunity), a breakthrough might be within grasp as part of a U.N.-sponsored effort to bring greater security to the whole region.

The difficulties involved in shaping the peace will be many, and it will be no time for hubris on the part of the United States and its allies. But their military achievement has shown determination, discipline and a keen sensitivity to the region's complexities. These qualities, if maintained into the postwar months, would go far in helping to shape a peace that could last.