Defense Secretary Donald H. Rumsfeld said Monday that while Iraqi President Saddam Hussein's whereabouts may not be known, "we do know he no longer runs much of Iraq."

"The circle is closing, their options are running out," Rumsfeld said of Saddam and his top lieutenants.

Looking beyond Saddam, Rumsfeld said that planning is under way to turn over to Iraqis control of several government ministries other than defense and intelligence.

"It's pretty well sorted through," Rumsfeld told a Pentagon briefing.

U.S. officials envision turning over administration of Iraq to an interim Iraqi government at some point, leading to eventual elections.

Rumsfeld cautioned against news accounts suggesting that the presence of chemical weapons had been confirmed. "Almost all first reports we get turn out to be wrong," he said.

"We don't do first reports and we don't speculate," he said.

Other defense officials said Monday that the military was testing samples from a site in Iraq where soldiers found possible chemical weapons. Testing at laboratories in the United States has to be completed before the presence of chemical weapons could be confirmed, those officials said.

Air Force Gen. Richard Myers, chairman of the Joint Chiefs of Staff, said there were now 125,000 coalition troops inside Iraq and that all but "a couple of dozen" of the Iraqi military's tanks had been destroyed.

Rumsfeld was asked when U.S. forces could declare victory, and whether it would depend on capturing or killing Saddam. "I don't think it would necessarily hinge on Saddam," he replied.

But the secretary added that "at that point where he's unable to run his country, the regime would have been changed."

Rumsfeld suggested that complete victory would likely come "later rather than sooner, simply because it's a big country."

Rumsfeld and Myers both expressed optimism that the notorious Iraqi general known as "Chemical Ali" (Ali Hassan al-Majid) had been killed in a U.S. airstrike on his home in southern Iraq. They showed reporters a video of the missile attack.

"We believe that the reign of terror of Chemical Ali has come to an end. To Iraqis who have suffered at his hand, particularly in the last few weeks in that southern part of the country, he will never again terrorize you or your families," Rumsfeld said.

He said that British forces operating in the south now control much of Basra, Iraq's second largest city.

"Despite the dire predictions about the forces and the plan, coalition forces have come a long way in a short time. But there is dangerous and difficult work ahead," he said.

Rumsfeld insisted that the United States did not intend to indefinitely administer Iraq, and that the plan was to turn government over to an Iraqi-run interim government as soon as practical. "The United States is not going to impose a government on Iraq," Rumsfeld said.

Rumsfeld and Myers gave an update on the war as U.S. troops roared into Baghdad for the third day in a row. U.S. officials said it showed they could move in and out of the capital at will.

The show of massive force is part of a plan to eliminate resistance from Saddam's forces piece by piece, in hopes of avoiding an all-out battle for Baghdad, home to some 5 million Iraqis.

One difference in the latest thrust into the capital, following forays Saturday and Sunday, is that Americans might stay a bit longer, one official said, adding it might be a matter of hours, not days. Officials stressed that the commander on the ground would make the decision based on developments and had the ability and mobility to decide whether he would move around the area, or move along.

Also, "it proceeded on a much slower pace and did a lot more activity than we did in our previous entry," said Navy. Lt. Mark Kitchens, a spokesman for the U.S. Central Command at its Qatar headquarters. Asked if troops might stay in Baghdad, "I think that would be a possibility."

"I think ... the military commanders will slowly but surely take on various parts of the city, go in and clean it out and make it safe for the Iraqi civilians that want to live there," Marine Gen. Peter Pace, vice chairman of the Joint Chiefs of Staff, had said hours before Monday's assault.

On Sunday, troops began flying into the captured international airport outside Baghdad, destroyed a Republican Guard headquarters and began to deploy a force of Iraqi exiles and dissidents who are to make up the core of a new national army.

U.S. soldiers and Marines surrounded Baghdad to try to prevent regime leaders from getting out and Iraqi troops reinforcements from getting in, Pace said in a round of television interviews Sunday. He acknowledged it wasn't "an impenetrable cordon" around the city.

"It is certainly true that we have huge amounts of combat power around the city right now, and that we have over a thousand planes in the air every day," he said. "So if it moves on the ground and it takes aggressive action, it's going to get killed."

Asked what tactic commanders planned in the coming battle to unseat Saddam, he said it was essentially more of the same but in a smaller space.

Air power will shape the battlefield and destroy Iraqi forces and equipment; ground troops will force Iraqi fighters to move, then air strikes will attack again, Pace said.

U.S. Central Command reported that 2,000 to 3,000 Iraqi fighters were killed in the first thrust — a sweep Saturday by the 3rd Infantry Division through the city's southwestern industrial section.

Over time, the thinking goes, Saddam and his inner circle would completely lose their ability to communicate with their remaining military forces, and would be unable to control anything except their own defenses.