"We're seeing a cellular organization of six to eight people armed with (rocket propelled grenades), machine guns, etc., attacking us at some times and places of their choosing and other times we attack them at times and places of our choosing," Abizaid told reporters here Wednesday.

"I think describing it as guerrilla tactics being employed against us is ... proper ... in strictly military terms," said Abizaid, who took over from General Tommy Franks, who headed the Central Command before and during the war.

It was the first time a member of the US Armed Forces admitted in public that the constant attacks US troops remaining in Iraq while interim leaders try to set up a new government in Baghdad constituted guerrilla tactics.

Abizaid also said the United States had been surprised by the total collapse of Iraq's security forces at the end of the war.

"All of us were a bit taken aback by the complete destruction of the Iraqi army and the near total dissolution of Iraqi security institutions, especially police," he said.

The resulting lack of local security forces has added to the burden that US troops are facing in Iraq.

US-led forces in Iraq were on high alert Thursday, the anniversary of the 1968 seizure of power by Saddam Hussein's Baath party. Hussein, who was not captured during the Iraq war and is widely believed to still be alive, is suspected of being behind some of the recent attacks on US troops.

The death of a US soldier in an attack Wednesday on a military convoy was the 147th since US troops invaded Iraq March 20, equalling the number of US dead in the 1990-1991 Gulf War and raising alarm about the occupation's high cost in American lives.

On Tuesday the US Third Infantry Division was unexpectedly ordered to remain in place, its scheduled return to the United States postponed due to the state of insecurity in Iraq.

Everyone had hoped for their return "relatively soon", along with troops from the First Marine Division "provided certain expectations were ... met on the security front," Abizaid said.

"Once we started to understand that environment, we knew that we were going to have to extend people longer than we had hoped."

He stressed the decision to remain was a tactical one and was not being forced on the US military.

"War is a struggle of wills," he said. "They are not driving us out of anywhere."

The White House on Wednesday downplayed reports of slumping morale among US troops in Iraq.

"The troops recognize that what they are doing is very important: Helping secure and stabilize Iraq so that it can move towards freedom and democracy," said Scott McClellan, chief spokesman for US President George W. Bush.

"Our troops are making a great sacrifice, and the president is grateful for their sacrifice," he said. "We will continue to make sure they have all the resources and support they need as they do their job."

WAR.WIRE