Even as the threat of all-out combat recedes, however, US troops were involved in clashes in the northern city of Mosul that have left 19 people dead over the past two days.

Iraqi witnesses said on both days that US troops fired into crowds, while US officers said their troops were returning fire at gunmen.

"I'm not prepared to judge on either site whether it's a lack of fire discipline that was the cause or what was the cause," said Major General Stanley McChrystal, the vice director of operations of the Joint Staff.

"I will say it highlights the complexity of the situation," he said.

Combat remains a possibility in some parts of the country as US or British forces spread out to areas that were bypassed in the fighting for Baghdad, McChrystal said.

He mentioned a town north of Tikrit that has not been visited by US forces, and that until recently major elements of Iraqi forces had been holed up Ar Ramadi west of Baghdad and Al Qaim on the Syrian border.

"So there is potential in those locations for some fights," he said. "But most areas are transitioning, going after pockets of death squads, toward dealing with elements that want to rise up and cause threats to either the new Iraq or coalition forces."

"I think it is transitioning very rapidly to support and stability," he said.

Army General Tommy Franks, the commander of US forces, has begun to send back aircraft carriers and warplanes as the need for them falls off.

McChrystal confirmed that the 1st Cavalry Division from Fort Hood, Texas will not be deploying to Iraq as scheduled, but military police units and other support units attached to it would still be shipping out.

The 1st Infantry Division and the 3rd Armored Cavalry Regiment were moving into the region, and the 4th Infantry Division is on the ground, he said.

"I expect as he (Franks) goes into the support and stability operations, he will divide it (Iraq) into sectors -- a marine sector, an army or V Corps sector, and then the coalition forces operating as he sees fit.

"And he'll have special operations forces available to him throughout to augment or complement regular forces," he said.

SPACE.WIRE