US starts Iraq withdrawal after defeat of Islamic State
Over the past week dozens of American soldiers have been transported from Iraq to Afghanistan on daily flights, together with weapons and equipment.
Two Iraqi officials confirmed to The Associated Press that the US coalition and Iraqi government have reached an agreement about withdrawing troops for the first time since the war against IS was launched.
The official process of withdrawing forces has not begun, they added.
"Continued coalition presence in Iraq will be conditions-based, proportional to the need and in coordination with the government of Iraq," US coalition spokesman Army Col. Ryan Dillon told the AP when asked for comment.
One senior Iraqi official close to Prime Minister Haider al-Abadi said 60 percent of all American troops currently in the country will be withdrawn, according to the initial agreement reached with the United States.
The plan would leave a force of about 4,000 US troops to continue training the Iraqi military. A Pentagon report released in November said there were 8,892 US troops in Iraq as of late September.
The US first launched airstrikes against IS in Iraq in August 2014 in a military intervention described as "limited".
The US-led coalition's presence in the country grew steadily as Iraq's military struggled to roll back the Islamic State.
"We've had a recent change of mission and soon we'll be supporting a different theater of operations in the coming month," US Army 1st Lt. William John Raymond told the AP at Al-Asad airbase.
The partial withdrawal of US forces comes three months ahead of national elections in Iraq, where the indefinite presence of US troops continues to be a divisive issue.
Abadi has long struggled to balance the often competing interests of Iraq's two key allies - Iran and the US.
The US has closely backed Iraqi military victories over IS, including recapturing the city of Mosul, but Iraq's powerful Shia-led paramilitary forces have close ties to Iran and have called for the withdrawal of US forces.
Abadi has previously stated that Iraq's military would need US training for years to come.
There were some 170,000 American troops in Iraq in 2007 at the height of the surge of US forces to combat sectarian violence unleashed by the US-led invasion of the country.
US troop numbers eventually wound down to 40,000 before the complete withdrawal in 2011.