Once the shooting stops, what then? From the viewpoint of everyone save the Iraqis and their friends, this war's first days have gone impressively well. An early conclusion, on victorious terms, seems all but assured. In the aftermath, what can then be tried to keep the peace?

By no means is it premature to chew over such a question. The war exploded out of aggression unforeseen, grievances unchecked and conflicts unresolved. After the war ends, many causes of the turmoil will still be bubbling away, demanding to be addressed while the world's eyes are focused on the region.Once Iraq decides that enough is enough, to whom does it surrender? Only one choice would be appropriate in the unique circumstances of this war: United Nations Secretary General Javier Perez de Cuellar.

This campaign to get Iraq out of Kuwait is, after all, an operation undertaken under U.N. auspices in the pursuit of a whole hatful of U.N. Security Council resolutions. If the campaign succeeds as well as appears likely, U.N. prestige and future stature will be considerably enhanced. It would be fitting, and it would bolster U.N. credibility for future crises, for Perez de Cuellar or his representative to accept a formal Iraqi surrender.

With the nations of the Middle East still stunned, but grateful (at least privately) that Saddam Hussein has been defanged, the early postwar weeks would offer a priceless chance to set up a peacekeeping mechanism. Iraq's integrity as a nation will need to be preserved: Any alternative would open up a power vacuum with potentially disastrous consequences.

Whether Saddam Hussein survives or not, a war-battered Iraq would be shaky, subject to internal convulsions and vulnerable to neighborly pressures. Rebellious Kurds will be heard from. Syria and Iran, neither the most benign of states, will be watching hungrily in the wings. Accordingly, guarding against new flare-ups - monitoring an initially shaky peace - will be a task of the highest priority.

Although American troops may be needed for some time to help patrol things (and to keep Israel reassured), Arab sensitivities would require that non-Western forces be given the bulk of the assignment. Such a multinational force under U.N. auspices, deployed around Kuwait and perhaps along selected Iraqi frontiers, might be needed for years. The cost to U.N. members for maintaining this guarantee of regional stability would be high, but not nearly as high as the cost of the war.

Successfully shaping a postwar security system for the gulf region would be unthinkable, of course, without redoubled efforts to gain progress on the Palestinian-Israeli dispute. Once a credible multinational security force were set up in the region, the prospects for breakthroughs on this issue might improve dramatically. Iraq's military threat will have, presumably, been removed. The Palestine Liberation Organization, its prestige battered, was further weakened by the assassination of two top leaders in Tunisia last week. Israel, shaken by the nearness of war, may be freshly alert to new ideas for its own security.

Could a strengthened U.N. peacekeeping force fill a constructive role in supervising an Arab-Israeli accord? There is no inherent reason why not. To reassure Israel, a hefty American contingent would probably be necessary, which would hardly go down well with the militant Palestinians. But a credible Palestinian settlement, to be backed up for years, if necessary, by a U.N. presence on the ground, would answer many Palestinian dreams, perhaps to the point that threats of terror would begin to taper off.

None of this assumes that the end of war with Iraq will automatically open the gates for a vigorous new U.N. role as a prime agent of peace and security. But the chances for a new initiative are especially compelling, and, well before the battles conclude, nations in the U.N. coalition should be shaping a long-term strategy for Iraq and its neighbors in a postwar time.