News of his whirlwind trip was not even released until Air Force One had already left for fear of the sort of missile fire that forced an emergency landing by a DHL civilian cargo jet last week.

The visit came as it emerged the Pentagon is to send an extra 3,000 US Marines to Iraq, as the war-shattered country continues to reel from mounting attacks by insurgents on US forces and Iraqi civilians.

Troops of the 1st Armoured Division which patrols the area around the Iraqi capital threw their arms in the air and cheered when Bush arrived at their US holiday feast.

"I was looking for a warm meal somewhere, thanks for inviting me to dinner," quipped the US commander in chief to deafening applause from the troops.

"I can't think of a finer group of folks to be having Thanksgiving dinner with," Bush told the soldiers from the 2nd Armoured Cavalry Regiment.

"I bring a message on behalf of America, we thank you for your service," he told the troops, who have come under regular attack during the persistent insurgency that has dogged the US-led occupation for the past seven months.

Bush, wearing a blue shirt and a grey bomber jacket and with his eyes moist, had a defiant message for the militants who have peppered the coalition military with guerrilla attacks.

"We didn't charge hundreds of miles into the heart of Iraq, and pay a bitter cost of casualties, defeat a ruthless dictator and liberate 25 million people only to retreat before a band of thugs and assassins," he said.

"Those who attack our coalition forces and kill innocent Iraqis are testing our will.

"We will prevail. We will win because our cause is just ... We will win because you're part of the finest military ever assembled. We will prevail because the Iraqis want their freedom."

Bush, who was accompanied by his hawkish national security advisor, Condoleeza Rice, dined with his top civilian and military officials, administrator Paul Bremer and ground forces commander Lieutenant General Ricardo Sanchez.

"I have a message for the Iraqi people," he said. "You have the opportunity to seize the moment and rebuild your great country ... The regime of Saddam Hussein is gone forever."

In a sign of the extraordinary security precautions, television reports said US authorities would have called off the visit had news been leaked in advance.

Bush's lightning trip followed a two day visit by British Foreign Secretary Jack Straw earlier this week to Iraq, which was also kept secret until he had left Baghdad for the calmer British-controlled city of Basra.

The surprise trips by Straw and Bush marked a spectacular show of defiance by London and Washington in the face of the persistent resistance, which has included a rocket attack on the Baghdad hotel where US Deputy Defense Secretary Paul Wolfowitz was staying.

Thousands more US marines were also set to be sent to Iraq, where the US fatalities since the May 1 declaration of an end to major hostilities now far exceed those during the March-launched war itself.

Defense Secretary Donald Rumsfeld has approved the deployment of three new Marine battalions, the Pentagon said Wednesday, meaning about 3,000 extra troops on top of those already planned for rotation with existing forces in Iraq.

In a further sign of the violent instability still plaguing Iraq, a rocket-propelled grenade slammed into the second floor of the Italian embassy in Baghdad overnight but failed to explode and caused no casualties.

The attack came a mere two weeks after an explosives-laden truck detonated at an Italian military police base in Nasiriyah, southern Iraq, killing 28 people including 19 Italians.

The US 101st Airborne Division mourned the latest US troop fatalities -- two of its soldiers killed in a shooting ambush in the northern city of Mosul last week in which witnesses said they had their throats slit.

An Iraqi motorist was gunned down in error by US troops in the heavily guarded main square of the northern oil centre of Kirkuk in the sixth such incident of recent months, police said.

In a political setback for the coalition, the religious leader of Iraq's Shiite Muslim majority, Grand Ayatollah Ali Sistani, Thursday demanded immediate elections at all levels of the Iraqi administration.

The top cleric rejected the coalition's insistence that elections of any sort were impossible before 2005, arguing that the ration-card system in force here for more than a decade gave ample basis for an electoral register.

Sistani "wants the Iraqi people to be consulted," the current head of the Governing Council, Jalal Talabani, told reporters after a meeting with the top cleric in this central holy city.

"He wants elections to be held for the municipal councils as well as the legislative council," said Talabani, a pro-US Kurdish politician.

US Secretary of State Colin Powell said that the United States would not seek a new UN resolution on Iraq straight away, indicating that the administration feels it has enough authority.

Meanwhile, in its continuing hunt for Saddam and former officials of the ousted leader's regime, the US military said it arrested a former bodyguard of Saddam during a raid north-west of Baghdad.

US troops said Wednesday they had captured a wife and daughter of Izzat Ibrahim al-Duri, Saddam's deputy, whom they accuse of masterminding anti-coalition attacks.

Japan's reconnaissance mission to Iraq returned home Thursday, and was expected to report that it was safe enough to send Japanese ground troops to the southern city of Samawa.

TERRA.WIRE