US officials said they were preparing for the final major military operation of the war in Iraq, an assault o­n President Saddam Hussein's hometown of Tikrit.

But signs were increasing today that an all-out attack might not be necessary amid indications that defenses in the city were crumbling, much as they did in the other major northern cities the coalition won this week.

Ahead of the planned advance by US-led troops, coalition aircraft continued striking Republican Guard positions in Tikrit, and roadblocks were erected to keep Iraqi leaders fleeing Baghdad from reaching the city, the last redoubt of the ruling Baath Party.

Coalition forces were reported to be within 60 miles of the city. With none known to be in the city itself, hard information about defenses there was hard to come by, and much of it was contradictory. But as time wore o­n Saturday morning, it looked more and more as though Tikrit could possibly fall without much of a fight.

Abandoning positions

Intelligence from a Predator reconnaissance drone indicated that Saddam's followers could be abandoning their posts, US officers were quoted as saying in an article The Washington Post published Friday night o­n its Web site.

Videotape showed no defensive preparations, said the officials, who were not identified. Instead, it showed looting in the streets.

The Telegraph of London reported in its Saturday editions that British intelligence reports indicated that the leadership may be ripping itself apart with internecine fighting. It said special operations forces north of the city found five light aircraft hidden under camouflage netting, which senior US military officials said might have been intended to help leadership figures escape.

US officials have said for more than a week that they expected Saddam and his followers to make their last stand at Tikrit, where many of them were reported to have fled after the fall of Baghdad earlier this week. For now, they are not ruling out a battle for Tikrit.

One of Saddam's longtime confidants, Izzat Ibrahim al-Douri, is believed to have moved missiles into the Tikrit area to bolster its defenses, The Associated Press reported, while US officials said they had seen remnants of Iraqi units join up with other stragglers in and around Tikrit, making what some referred to as "composite forces" still defending the city.

But military planners at US Central Command forward headquarters in Doha, Qatar, said Friday that the bombardment by US warplanes may have battered Republican Guard units there into submission.

For the first time, they began raising the possibility that Tikrit could fall quietly. The AP quoted defense officials in Washington as saying there were "no obvious significant forces in Tikrit."

It remained unclear whether Saddam was hiding in Tikrit, had fled elsewhere or had died in a US attack aimed at a Baghdad building Monday.

Officials at the Pentagon told NBC News that o­n the list of wanted leaders, there were "three or four known dead" but that Saddam was not among them.

One of the officials said leaders of Saddam's regime, facing the prospect of war crime tribunals if they were captured, had undoubtedly left the country, most likely for Syria. US forces are trying to intercept them at the border, but they do not have enough personnel in the area to block all crossing points, the official said.

Bush urges caution

US officials had also expected tough battles in two other northern cities, Kirkuk and Mosul, but both fell quietly this week. Administration officials said Friday, however, that it was still too soon to declare victory.

"The war will end when [Gen.] Tommy Franks (photo right) says we've achieved our objective," President Bush said in a suburb of Washington after visiting Marines, soldiers and sailors wounded in the conflict.

White House press secretary Ari Fleischer said that while "the regime has lost control" of the country, "it is still a battlefield. The military mission remains under way even though the regime has all but disappeared."

While Iraqi leaders were no longer in control, US officials said, their whereabouts were uncertain. The Iraqi leaders are "either dead or running like hell," Franks, the Army general who is commanding the allied war effort, said in Afghanistan.

Policing challenge growing

While coalition military forces were clearly gaining command o­n the battlefield, the tough policing challenge facing them in a nation riven by religious and ethnic differences was becoming more apparent.

Chaos and widespread looting were reported in Mosul and in many parts of Baghdad as coalition troops lacked the manpower to fill the vacuum left by Saddam's vanishing regime.

Defense Secretary Donald Rumsfeld, in a briefing Friday at the Pentagon, acknowledged that some cities were experiencing a period of "untidiness," but he suggested that it was o­nly a transitional phase o­n the way to freedom from Saddam's rule.

In Mosul, looting erupted Friday after Iraqi army units guarding the city vanished without a fight. MSNBC.com's Preston Mendenhall reported that 100 to 200 U.S. special operations personnel and Kurdish "peshmerga" fighters who rolled into Mosul, Iraq's third-largest city, found no resistance.

"We offered capitulation, but ... the Iraqi army evaporated, so there has been no formal capitulation or cease-fire," Lt. Col. Robert Waltemeyer, commander of an Army special operations unit in northern Iraq, said at a news conference in Mosul. "They may have just melted into the population."

Residents said they that feared the city of 600,000 was falling apart and that they were afraid to stay for the night.

Kurdish fighters complained that the coalition force was insufficient to keep order.

"We informed the Americans that they needed to come immediately" to help with security, said Rozgar Murishawez, the Kurdish commander for the Mosul region. "But we do not have enough of them with us."

US forces are stretched thinner in the north than they are in Baghdad and other cities in southern Iraq, and they have depended o­n the Kurds to bolster the coalition presence in the north.

Kurdish fighters in Kirkuk

Mosul fell Friday morning o­nly a few hours after Kirkuk, which is considered a prize because of its vast oil fields, fell with little resistance as Kurdish fighters marched into the disputed city.

The operation exposed another thorny problem for Washington as the sight of the Kurds celebrating in Kirkuk was viewed with great unease in neighboring Turkey. Shortly afterward, Turkey announced that it reached an agreement with Secretary of State Colin Powell that the peshmerga forces would be forced to leave Kirkuk quickly.

Turkey is worried that the Kurds, freed of the threat from Saddam's forces, would assert control over Kirkuk, which they view as their historic capital, and use its oil wealth to finance a new state. That would inspire Turkey's large Kurdish minority to fight for independence, Turkish leaders fear.

So grave is the perceived threat that Ankara has threatened to move its own forces across the border if Kurds show any signs of staying in the city.

NBC News'

Tom Aspell reported from Kirkuk that US forces told the peshmerga to leave the city but that there was no indication o­n the streets that the fighters were pulling back.

Complicating the picture, hundreds of Kurdish civilians from their autonomous region in the far northeast also streamed into Kirkuk o­n Friday, delighted at the chance to see friends and relatives for the first time in years.