|Joe Biden, US vice-president said that 50,000 troops would remain in Iraq [AFP]
The United States changed commanders in Iraq in a ceremony that began the final phase of its military involvement in the country.
Addressing soldiers at Camp Victory outside Baghdad on Wednesday, a day after the US combat role in Iraq officially ended, Joe Biden, US vice-president said he was confident that the worst days of the conflict were over.
"Operation Iraqi Freedom is over, but American engagement with Iraq will continue.
"This ceremony not only marks the change of the command but the start of a different chapter in the relationship with Iraq,' said Biden.
Biden said he was confident the various factions in Iraq will form a workable coalition and bring stability to the country.
"Iraqi troops are taking lead responsibilities for their country's security. We kept a promise, a promise made to the American people and to the people of Iraq by drawing down our forces to roughly 50,000, and we are on track to remove all of our troops by the end of next year according to the agreement signed by President Bush with the Iraqi government."
The military handover marks the start of Operation New Dawn which is seen as the last phase of a war that began with the US-led invasion of Iraq in March 2003.
More than 165,000 troops were based in Iraq during the peak of the invasion in 2007.
Newly promoted Lloyd Austin, an US army general, took over in the change of command ceremony in Baghdad.
He noted "hostile enemies" continued to threaten Iraq and pledged that the US commitment would not change.
Austin, who most recently served in Iraq as commander of troop operations from 2008-09, replaces General Ray Odierno, who is heading to Virginia to take over the Joint Forces Command after about five years in Iraq.
On Tuesday night, Barack Obama, the US president, announced the shift from combat operations to preparing Iraqi forces to assume responsibility for their own security, after seven years of war.
More than 4,400 US troops and an estimated 100,000 Iraqis were killed in a war said to have cost billions of dollars.