When President Bush announced the beginning of military action in Iraq earlier this month, he assured the world the United States had no evil intentions in that country.

"We come to Iraq with respect for its citizens, for their great civilization, and for the religious faiths they practice. We have no ambition in Iraq, except to remove a threat and restore control of that country to its own people," Mr. Bush said.

But the president's advisers have confirmed that in addition to humanitarian aid and the possible assistance of the United Nations, military occupation of Iraq will be necessary for some time after the fighting has ended.

During a Congressional debate of the Iraqi war resolution, Democratic Senator Joseph Biden remarked that, "the easy part is going to be, in a bizarre sense, taking Saddam out. The hard part is what you do after that."

James Miskel, who teaches courses in peacekeeping and nation-building at the U.S. Naval War College in Newport, Rhode Island, said getting involved in countries' postwar destiny is risky and expensive.

"We end up using military forces for it, and I don't think using military forces are the optimum tool, because they're designed to do other things. People need to understand how hard it is to build nations. It's hard enough to keep people from shooting each other and factions to stop fighting each other. It's quite a bit more complicated to build systems and structures in the local economies so that people will have a stake in the status quo even after the peacekeepers leave," he said.

Professor Miskel concedes that lengthy military occupation will be necessary in Iraq, if only to curb turf wars and revenge-taking.

But Mr. Miskel said he anticipates an easier and faster reconstruction in Iraq than in Afghanistan - another war-torn nation rife with factionalism.

"Iraq had a bigger middle class, a higher level of literacy. The oil's still there, so they can "plug back in", so to speak, to the world marketplace [more quickly] than Afghanistan could, because Afghanistan wasn't 'plugged in' in the first place and doesn't have much to offer the world community, whereas people want what Iraq can sell," he explained.

To assuage those who fear a grab for oil was an underlying motivation for invading Iraq, James Miskell of the U.S. Naval War College has suggested someone besides the United States OPEC, perhaps be allowed to decide how much Iraqi oil may be sold during the American postwar occupation.

Ray Jennings is a senior fellow at the United States Institute of Peace, a nonprofit federal institution created by Congress. He has just completed a lengthy analysis of the likely road ahead in postwar Iraq, compared with American nation-building in Afghanistan and years earlier after World War II - in Japan and Germany. Almost inevitably, Mr. Jennings said, the job is harder, and takes far longer, than anyone planned.

"The occupation of Germany and Japan was seen by the domestic public in the United States as the unfortunate but necessary end to a very trying historical episode. It's not quite the same now. There is more indecision. And certainly in the international arena, there is a great deal of uncertainty about whether this is an appropriate course of action. And whereas that may not make as big a difference in a military campaign, it certainly can make a big difference when you're talking about spending a billion dollars a month in postwar reconstruction over eight to 10 years," Mr. Jennings said.

Ray Jennings said the days immediately after the end of hostilities are critical. An occupying power must establish stability, security, and the rule of law. Failure to do so, said Mr. Jennings, could waste months of careful postwar planning. With firm but just control in the smoldering aftermath of war, Mr. Jennings adds, democratization is possible, even in a traditionally repressive society like Iraq's.

"State Department experts on Germany and Japan back in the occupations of those two countries after World War II thought they were incapable of democracy. They have since become rather vibrant democracies," he explained.

Ray Jennings at the United States Institute of Peace said United Nations assistance in reconstructing Iraq will be important to a successful outcome.

"It may be the case that the United States will be able to repair some damage on a diplomatic front with a number of our traditional allies when it comes to development - to hand off the kind of unilateral effort that we may make on the front end toward a multilateral presence. That may mean, for example, that the United Nations will establish an authority quite similar to what we saw in Kosovo, so that you don't have a U.S. military governor for a long period of time," Mr. Jennings said.

Others are also peering into the critical days that will follow the fighting in Iraq. Simon Chesterman of the International Peace Academy in New York has written of Americans' typical impatience for results. He says that what he calls the nation's "congenital aversion to nation-building" may intensify as it turns its attention inward, to a presidential election campaign less than two years away.

Columnist Bob Herbert reminded readers of The New York Times that it will not be U.S. military and government officials alone who will be enmeshed in postwar Iraq. He said private companies will be busy restoring Iraqi oil production and rebuilding Iraqi infrastructures that might have been damaged during the war. And many other observers have written cautionary tales of the daunting challenge not just rebuilding infrastructure and assisting the victims of war but also coping with an especially volatile mixture of contending groups inside and outside Iraq.