According to the Iraq Coalition Casualty Count website, there have been 1,996 US casualties since American-led forces marched into Iraq in 2003, most killed in the insurgency that has gripped the country since Saddam was toppled.
"Two thousand is a significant number and will resonate with the US public," said Charles Heyman, a senior defence analyst at Janes's Information Group in London. "There is no doubt whatsoever about that."
"It will also resonate with the insurgents," he told AFP.
The Pentagon website, which was last updated on Friday, gives a figure of 1,983 dead and more than 15,000 injured, although it does not include at least four killed since then. Of the dead, 1,547 were killed in action and 436 in non-combat situations.
However, the number of US dead is dwarfed by the estimated 30,000 Iraqis who have been killed since the invasion of March 2003, most of them civilians.
"To put it into perspective, it's not that much when you consider how many troops have come through here," US Sergeant Frank Purcell told AFP after a patrol in southern Baghdad.
But Sergeant First Class Joseph Baker added: "That's exactly 2,000 too many."
Between 26,661 and 30,018 Iraqi civilians have died since the invasion, according to Iraq Body Count, which tracks press reports of unrest in the country.
In September alone, 4,373 Iraqis were killed in various attacks, including strikes by insurgents and shootings by multinational forces, of which 3,015 were civilians, figures from the defence, health and interior ministries showed.
As the US count climbed, Bush and US Secretary of State Condoleezza Rice have sought to contain discontent.
On October 6, Bush criticised "self-defeating" observers who suggested the US should withdraw its 140,000 troops.
"In Iraq, there is no peace without victory. We will keep our nerve and we will win that victory," Bush said.
The deadliest strike against US forces was in December when 22 people, including 18 Americans, were killed by a suicide bomber in the mess hall at a US military base in Mosul in an attack claimed by al Qaeda linked Ansar al-Sunna Islamist group.