by Deborah Haynes

The number of US troops to die in Iraq since the invasion began five years ago hit 4,000 last night after a roadside bomb in Baghdad killed four soldiers.The morbid milestone will likely strengthen calls for US forces to be withdrawn from the country; a contentious topic in this year's Presidential elections.

A US military spokesman played down the significance of the 4,000th death, which followed a day of bombings and rocket fire across the country that killed at least 60 Iraqis and left many more wounded.

"No casualty is more or less significant than another; each soldier, marine, airman and sailor is equally precious and their loss equally tragic," said Rear Admiral Gregory Smith.

One soldier was also injured when the roadside bomb - the biggest killer of US forces in Iraq - struck a patrol in south Baghdad.

As well as 4,000 dead, at least 29,000 US servicemen and women have been injured in the Iraq war, which entered its sixth year last week, according to the independent Web site www.icasualties.org.Underscoring the brutality of an insurgency that flared in the aftermath of the invasion, the majority of American casualties occurred after George Bush announced the end of "major combat" in Iraq on May 1, 2003.

Despite the ongoing challenges, the President declared on the eve of the fifth anniversary of the war that the United States was on track for victory, while acknowledging the "high cost in lives and treasure".

Some 158,000 US forces are based in Iraq. The United States and Britain hoped for a speedy victory when they entered the country on the night of March 20, 2003 in the now discredited quest to find weapons of mass destruction.

Saddam Hussein's army easily fell and the regime quickly crumbled, but within months of establishing control, US forces found themselves up against a bloody insurgency that continues to claim lives.

The 1,000th US soldier to die was in September 2004, in the midst of a presidential election that returned Mr Bush to office for a second term.

The toll climbed to 2,000 in October 2005 as Sunni Arab insurgents battled to oust the Iraqi Government, and 3,000 in December 2006, before the US President unveiled a plan to send 30,000 more troops to Iraq to quell violence that has killed tens of thousands of Iraqis and displaced millions more.

Demonstrating the ongoing dangers, rockets and mortars pounded Baghdad's fortified Green Zone yesterday in a rare volley of attacks that injured at least five people. The nationality of those wounded was not immediately clear.

Up to 17 Iraqi civilians were also killed by rounds that most likely fell short of the sprawling compound, which houses Iraq's Government and also the US and British embassies.

In other violence, a suicide driver in the northern city of Mosul detonated a car packed with explosives in front of an Iraqi army building, killing 15 Iraqi soldiers and injuring 45 other people.

A separate suicide car bomb in Baghdad left seven people dead and 14 wounded, while another seven were killed when gunmen opened fire on passengers waiting for buses in the southeast of the capital.

Attacks across Iraq have dropped dramatically since the summer thanks to the US surge, as well as a ceasefire by the powerful Shia al-Mehdi Army militia and a decision by Sunni fighters to side with the US military against al-Qaeda. However. US commanders warn that the gains are fragile.

General David Petraeus, the top US commander in Iraq, and Ryan Crocker, the American Ambassador, are due to present a report on the situation in the country to Congress early next month. All eyes will be on potential recommendations for further troop reductions.

The United States already plans to withdraw more than 21,000 soldiers from Iraq by the end of July - a draw down that remains on track despite the recent wave of violence. Both Democratic hopefuls in the Presidential race, Barrack Obama and Hillary Clinton, favour a speedy pull-out, in contrast to John McCain, the presumed Republican nominee.
© 2008 The Times Online