Iraqi power brokers were free to look ahead to Iraq's postwar future after the relatively smooth occupation of Tikrit signaled the significant combat phase of Operation Iraqi Freedom had come to a close.

• Maps: Iraq | Baghdad

Saddam Hussein's hometown was the last major Iraqi city to succumb to overpowering U.S.-led ground and air forces.

"I would anticipate that the major combat engagements are over," Maj. Gen. Stanley McChrystal said. Tikrit fell with no sign of the ferocious last stand by Saddam loyalists that some military planners had feared.

Meanwhile, Secretary of State Colin Powell became the latest senior administration official to accuse Syria of harboring former members of Iraq's regime and of maintaining a chemical weapons program.

"Of course, we will examine possible measures of a diplomatic, economic or other nature as we move forward," Powell told reporters.

Fayssal Mekdad, Syria's deputy ambassador to the United Nations, denied the U.S. allegations.

"There is no cooperation. We have no chemical weapons," he said.

In London, British Prime Minister Tony Blair said Syrian President Basher Assad had personally assured him that his government "would interdict anybody" crossing the border from Iraq. "And I believe they are doing that," Blair told the House of Commons.

But Syrian officials continued to dodge mounting evidence the government had encouraged Arabs to cross the border into Iraq and fight coalition forces.

Anger rose in Tikrit on Tuesday as Marines tightened their hold over Saddam Hussein's hometown. Tanks barred people from crossing over a Tigris River bridge that was heavily damaged in an airstrike, and many helicopters flew overhead.

As looters ransacked a government agriculture building in Tikrit, about 90 miles north of Baghdad, infuriated residents complained to a reporter that the bridge into town had been blocked for days; many said they were hungry and sick, but U.S. forces would not let them go to a hospital across the river.

"The Iraqi people want to go to their own parts of their territory -- their own lands," one man yelled. "But the Americans are not letting them!"

A Marine in a passing convoy wouldn't comment on the situation in the town, referring questions to his commanding officer and saying only, "We're trying bring order."

"There was less resistance than we anticipated," Brig. Gen. Vincent Brooks told reporters, as American ground troops moved into the key city after days of punishing airstrikes.

American forces captured a key Tigris River bridge in the heart of town and seized the presidential palace without a fight as they rolled past abandoned Iraqi military equipment.

"We have had engagements, and we have defeated the enemy in every one of those engagements," said Capt. Frank Thorp, a spokesman at U.S. Central Command.

The operation inside Tikrit, Brooks added, "is really the only significant combat action that occurred within the last 24 hours." McChrystal told reporters, "I think we will move into a phase where it (combat) is smaller, albeit sharp fights."

A senior defense official told Fox News that Baath Party members and members of the Fedayeen Saddam had formed 100 small death squads in Tikrit. Several tribal leaders tried to negotiate a cease-fire with coalition forces but Baath officials resisted their efforts.

In Baghdad, Marines handed out flyers Tuesday, appealing to people to stay inside between evening and morning prayers, "to avoid placing coalition forces in a position where we must make a distinction between you and terrorist or criminal elements during a time of limited visibility."

The message stopped short of imposing a formal curfew, though Marines had discussed putting one in place during the weekend's rampant looting. The flyer advised people not to carry anything resembling a weapon, suggested drivers pull over to let military convoys pass, and called on public service workers to contact Marines at the Palestine Hotel.

Hundreds of Iraqis gathered outside the Palestine Hotel on Tuesday morning, pleading for law and order. Marines trying to placate the crowd moved out in front of the barbed wire they have laid in front of the hotel, but wound up struggling not to be thrust into it themselves as people pushed forward.

Marines had earlier searched rooms in the hotel, which serves as headquarters for many international journalists in Baghdad. They apparently detained four Iraqi men who didn't have proper identification. Marine Sgt. Jose Guillen confirmed troops entered rooms but offered no details, except to say the "building wasn't 100 percent safe."

 

Meanwhile, coalition forces had yet to enter scores of smaller towns scattered around Iraq. It was unclear what kind of condition those towns and villages were in, but there were no reports of looting or fleeing.

With Saddam and his two sons dead or in hiding, his regime gone and his armed forces routed, U.S. commanders took steps to reduce American firepower in the war zone.

A U.S. defense official said two of five aircraft carrier battlegroups in the region would soon be leaving, the USS Kitty Hawk returning to its base in Japan and the USS Constellation to San Diego. Each carrier has about 80 warplanes, including F/A-18 and F-14 strike aircraft as well as surveillance and other support craft.

The Air Force already has sent four B-2 stealth bombers home.

In a reminder of lingering hazards, two soldiers with the Army's V Corps were killed and two wounded when a grenade exploded accidentally at a checkpoint south of Baghdad and a third soldier was killed and another wounded in an accidental shooting near Baghdad International Airport, Central Command said.

With fighting on the wane, troops continued their search for remaining POWs as well as evidence of weapons of mass destruction.

Maj. Trey Cate, a spokesman for the 101st Airborne Division, said tests were planned on 11 shipping containers found buried near Karbala with lab equipment inside.

A team of experts from the CIA and Defense Intelligence Agency also has arrived in the Persian Gulf region to search for clues to the whereabouts of Capt. Scott Speicher, a Navy pilot shot down during the 1991 Gulf War, officials said.

U.S. official said an Iraqi nuclear scientist, Jaffar al-Jaffer, had surrendered to authorities in an unidentified Middle Eastern country in recent days and was being interviewed by Americans.

On Saturday, Saddam's top science adviser, Lt. Gen. Amer al-Saadi surrendered to U.S. forces.

More and more, efforts were turning to building a postwar Iraq. Officials made preparations for a meeting Tuesday in the southern city of Ur, said to be the birthplace of the biblical patriarch Abraham.

There, Iraqis from inside and outside the country will begin discussions on the shape of a future government.

At the Pentagon, Defense Secretary Donald H. Rumsfeld said "it's not possible to know how long" a process of stabilization will take inside Iraq.

Government offices and most stores remained closed in the capital, but many buses were running, packed with passengers. The first joint patrols moved through Baghdad during the day, with Marines and Iraqis working together.

Police Lt. Col. Haitham al-Ani said American troops and Iraqis would patrol in separate cars and that the Iraqis would be unarmed, at least for now.

At the same time, local leaders met in Baghdad to discuss security and plans to restore water and electricity to a city that has been without power for more than a week. One Shiite Muslim cleric, Ayad al-Musawi, told the meeting there should be "no Sunni, no Shiite, just one Iraqi nation."

He added, "God willing, we will be one hand, one voice and not betray each other."

The Associated Press contributed to this report.