The United States will help write an interim Iraqi constitution that embodies American values and will lead to the creation of a new government, America's chief postwar administrator in Iraq (search) said Sunday.

"We will write into that constitution exactly the kinds of guarantees that were not in Saddam's constitution," L. Paul Bremer (search) told ABC's "This Week" from Baghdad, the Iraqi capital.

"We'll have a bill of rights. We'll recognize equality for all citizens. We'll recognize an independent judiciary. We'll talk about a federal government.

"All of these things will be in the interim constitution which will also provide in a limited time, probably two years, for a permanent constitution to be written that also embodies those American values."

Bremer said Americans will work with the Iraqi Governing Council (search) in writing the interim constitution. There will also be a side agreement dealing with security and the presence of U.S. and coalition forces in Iraq, he said.

While the U.S.-led occupation will end, Bremer said the presence of coalition forces will not.

"Our presence here will change from an occupation to an invited presence," he said. "I'm sure the Iraqi government is going to want to have coalition forces here for its own security for some time to come."

On "Fox News Sunday," Bremer noted that President Bush has said the United States will not "cut and run" from Iraq. But Bremer said the length of time that U.S. troops will be there will be negotiated with the coming Iraqi government.

That agreement, he said, "will provide for our continued presence in Iraq to help them stabilize their country and to help them stay at peace with their neighbors. They have some pretty rough neighbors, and they're going to need our assistance, I think, for some time."

Defense Secretary Donald H. Rumsfeld, traveling in Asia, said the United States continues to plan to rotate a new contingent of troops into Iraq next year, with no final pullout date set yet. Accelerating the political process toward Iraqi self-rule will not affect military planning, he said.

The council on Saturday endorsed a White House proposal to form a provisional government by June. The transfer of power would provide President Bush a strategy to pull out U.S. troops as guerrilla warfare escalates.

Word of the new plan came on a day that two Black Hawk helicopters collided and crashed, possibly the result of enemy groundfire. The military says 17 American soldiers died, making the incident the worst single loss of life since Bush ordered the U.S.-led invasion to overthrow Iraqi leader Saddam Hussein.

"We did the Iraqi people a great favor by removing him, and so I wouldn't be surprised that any kind of violence is promoted by him, but I don't know," Bush said in an interview with David Frost for PBS-BBC's "Breakfast with David Frost."

Bush said the United States will not spend "years and years" in Iraq as a new government takes shape.

The president defended his administration's planning for postwar Iraq, saying it's "not a fair comment" that the United States was unprepared for winning the peace.

"This is nothing more than a power grab," he said about the recent violence. "There are some foreign fighters -- mujahedeen types or Al Qaeda, or Al Qaeda affiliates involved, as well."