Morning in downtown Baghdad has been marked by celebrations in the streets and looting of government buildings, as police and other remnants of the Saddam Hussein government failed to appear. Meanwhile, after a quiet night, U.S. forces swept through the suburbs of the Iraqi capital, facing only sporadic resistance.

In tanks, on foot patrols, and from the air, American forces are trying to dislodge snipers and other holdouts as the Iraqi defense of Baghdad steadily crumbles.

Thousands of U.S. Marines began early Wednesday to move block by block through Saddam City, a predominantly Shiite Muslim quarter of northeastern Baghdad, where they are attempting to squeeze out pockets of resistance by Iraqi forces.

American forces are still consolidating their positions in and around the Iraqi capital, and military officials now say they have isolated the city. On Tuesday, U.S. Army troops entered Baghdad for the first time from the north.

Meanwhile, thousands of Baghdad residents went out into the streets to celebrate, and to loot government offices. Television coverage from the city showed people running out of buildings carrying furniture, car parts and even flowers. People told television reporters they were celebrating the end of the Saddam Hussein regime.

While the securing of Baghdad continues, coalition commanders are now beginning to focus attention on another target - Saddam Hussein's home town of Tikrit, still a stronghold of loyalist troops. One officer at Central Command says Tikrit could be the scene of the Iraqi regime's last stand.

There is no word on whether Saddam Hussein survived a bombing raid on a building where he was reported to be meeting with his associates on Monday. But Pentagon spokeswoman Victoria Clarke says there appears to be confusion among the Iraqi leadership. "There are still some orders being given by somebody," she says. "They don't seem to be the best of orders. They don't seem to be very well coordinated."

The U.S. military has made degrading the Iraqi government's command and control structure a priority, and U.S. officials say the regime's defensive efforts lack coherence and cohesion.

As resistance to the allies diminishes, their attention is beginning to turn to Iraq's reconstruction. The United States and Britain confirmed at a summit Tuesday what they call a vital role for the United Nations in that process, but their plans are likely to fall short of what other European nations are demanding.

British Foreign Secretary Jack Straw was in Paris Wednesday morning to try to smooth over differences with France, a strong opponent of the war. Mr. Straw says the British and U.S. goal is the creation of a democratic Iraq, and for that to be achieved, allied forces need to play a role in the process. "The United States and United Kingdom forces are the reality on the ground in terms of providing security and stability over time," says Mr. Straw. "We have to remain there. It's our responsibility to stay there until these other processes are through."

France continues to insist that the U.N., and not the coalition, should play the leading role in the rebuilding of Iraq.