WASHINGTON, Oct. 10 — The White House is developing a detailed plan, modeled on the postwar occupation of Japan, to install an American-led military government in Iraq if the United States topples Saddam Hussein, senior administration officials said today.

The plan also calls for war-crime trials of Iraqi leaders and a transition to an elected civilian government that could take months or years.

In the initial phase, Iraq would be governed by an American military commander — perhaps Gen. Tommy R. Franks, commander of United States forces in the Persian Gulf, or one of his subordinates — who would assume the role that Gen. Douglas MacArthur served in Japan after its surrender in 1945.

One senior official said the administration was "coalescing around" the concept after discussions of options with President Bush and his top aides. But this official and others cautioned that there had not yet been any formal approval of the plan and that it was not clear whether allies had been consulted on it.

The detailed thinking about an American occupation emerges as the administration negotiates a compromise at the United Nations that officials say may fall short of an explicit authorization to use force but still allow the United States to claim it has all the authority it needs to force Iraq to disarm.

In contemplating an occupation, the administration is scaling back the initial role for Iraqi opposition forces in a post-Hussein government. Until now it had been assumed that Iraqi dissidents both inside and outside the country would form a government, but it was never clear when they would take full control.

Today marked the first time the administration has discussed what could be a lengthy occupation by coalition forces, led by the United States.

Officials say they want to avoid the chaos and in-fighting that have plagued Afghanistan since the defeat of the Taliban. Mr. Bush's aides say they also want full control over Iraq while American-led forces carry out their principal mission: finding and destroying weapons of mass destruction.

The description of the emerging American plan and the possibility of war-crime trials of Iraqi leaders could be part of an administration effort to warn Iraq's generals of an unpleasant future if they continue to support Mr. Hussein.

Asked what would happen if American pressure prompted a coup against Mr. Hussein, a senior official said, "That would be nice." But the official suggested that the American military might enter and secure the country anyway, not only to eliminate weapons of mass destruction but also to ensure against anarchy.

Under the compromise now under discussion with France, Russia and China, according to officials familiar with the talks, the United Nations Security Council would approve a resolution requiring the disarmament of Iraq and specifying "consequences" that Iraq would suffer for defiance.

It would stop well short of the explicit authorization to enforce the resolution that Mr. Bush has sought. But the diplomatic strategy, now being discussed in Washington, Paris and Moscow, would allow Mr. Bush to claim that the resolution gives the United States all the authority he believes he needs to force Baghdad to disarm.

Other Security Council members could offer their own, less muscular interpretations, and they would be free to draft a second resolution, authorizing the use of force, if Iraq frustrated the inspection process. The United States would regard that second resolution as unnecessary, senior officials say.

"Everyone would read this resolution their own way," one senior official said.

The revelation of the occupation plan marks the first time the administration has described in detail how it would administer Iraq in the days and weeks after an invasion, and how it would keep the country unified while searching for weapons.

It would put an American officer in charge of Iraq for a year or more while the United States and its allies searched for weapons and maintained Iraq's oil fields.

For as long as the coalition partners administered Iraq, they would essentially control the second largest proven reserves of oil in the world, nearly 11 percent of the total. A senior administration official said the United Nations oil-for-food program would be expanded to help finance stabilization and reconstruction.

Administration officials said they were moving away from the model used in Afghanistan: establishing a provisional government right away that would be run by Iraqis. Some top Pentagon officials support this approach, but the State Department, the Central Intelligence Agency and, ultimately, the White House, were cool to it.

"We're just not sure what influence groups on the outside would have on the inside," an administration official said. "There would also be differences among Iraqis, and we don't want chaos and anarchy in the early process."

Instead, officials said, the administration is studying the military occupations of Japan and Germany. But they stressed a commitment to keeping Iraq unified, as Japan was, and avoiding the kind partition that Germany underwent when Soviet troops stayed in the eastern sector, which set the stage for the cold war. The military government in Germany stayed in power for four years; in Japan it lasted six and a half years.

In a speech on Saturday, Zalmay Khalilzad, the special assistant to the president for Near East, Southwest Asian and North African affairs, said, "The coalition will assume — and the preferred option — responsibility for the territorial defense and security of Iraq after liberation."

"Our intent is not conquest and occupation of Iraq," Mr. Khalilzad said. "But we do what needs to be done to achieve the disarmament mission and to get Iraq ready for a democratic transition and then through democracy over time."

Iraqis, perhaps through a consultative council, would assist an American-led military and, later, a civilian administration, a senior official said today. Only after this transition would the American-led government hand power to Iraqis.

He said that the Iraqi armed forces would be "downsized," and that senior Baath Party officials who control government ministries would be removed. "Much of the bureaucracy would carry on under new management," he added.

Some experts warned during Senate hearings last month that a prolonged American military occupation of Iraq could inflame tensions in the Mideast and the Muslim world.

"I am viscerally opposed to a prolonged occupation of a Muslim country at the heart of the Muslim world by Western nations who proclaim the right to re-educate that country," said the former secetary of state, Henry A. Kissinger, who as a young man served as a district administrator in the military government of occupied Germany.

While the White House considers its long-term plans for Iraq, Britain's prime minister, Tony Blair, arrived in Moscow this evening for a day and a half of talks with President Vladimir V. Putin. Aides said talks were focused on resolving the dispute at the United Nations. Mr. Blair and Mr. Putin are to hold formal discussions on Friday, followed by a news conference.

Mr. Blair has been a steadfast supporter of the administration's tough line on a new resolution. But he has also indicated that Britain would consider France's proposal to have a two-tiered approach, with the Security Council first adopting a resolution to compel Iraq to cooperate with international weapons inspectors, and then, if Iraq failed to comply, adopting a second resolution on military force. Earlier this week, Russia indicated that it, too, was prepared to consider the French position.

But the administration is now saying that if there is a two-resolution approach, it will insist that the first resolution provide Mr. Bush all the authority he needs.

"The timing of all this is impossible to anticipate," one administration official involved in the talks said. "The president doesn't want to have to wait around for a second resolution if it is clear that the Iraqis are not cooperating."