An Associated Press reporter at the Al-Asad base in western Iraq saw troop movements reflecting the account by contractors.
"The battle against Daesh has ended and so the level of the American presence will be reduced", spokesman Saad al-Hadithi said. US troop numbers eventually reduced to 40,000 before the complete withdrawal in 2011.
Sources say coordination will continue between the USA military and Iraqi forces based on conditions not yet released.
American troops are leaving Iraq for Afghanistan as part of an agreement between Baghdad and the US-led coalition, contractors told AP.
While defeated on the battlefield, USA military planners have expected ISIS to switch to insurgent tactics, carrying out high-profile terror attacks in Iraq. The official spoke on condition of anonymity because he was not authorized to talk to the media. However, Iraq's Shiite-led paramilitary forces have called for a withdraw of USA forces, while Prime Minister Abadi has said that Iraq's military will need American training for years to come.
They include around 1,000 who surrendered during the battle for Hawija, the last IS urban stronghold in Iraq until its fall late past year, Iraqi Kurdish official Dindar Zibari told reporters. Iraq was the first country in United States military history where they were forced to withdraw in accordance to the initial agreement for the forces withdrawal from that country.More news: Powell sworn in as 16th chairman of Federal Reserve
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Raymond declined to say where his unit was being redeployed because the information has not yet been made public.
At that time Iraqi government headed by Prime Minister Nouri al-Maliki refused to extend the stay of U.S. troops in the country despite Washington's requests.
He said those forces do not possess any heavy weapons and they are now positioned in nine joint military camps with the Iraqi Army.
The second group, Kataib Hezbollah, has previously threatened to attack U.S. forces several times, denouncing their presence in Iraq as an occupation. Gen. Jonathan Braga, the coalition's director of operations, said in a statement.
However, the Iraqi officials said the process has not officially begun.
"Enabled by accelerated successes following the liberation of Mosul, the Coalition will shift its focus in Iraq from enabling combat operations to sustaining military gains against Daesh".
The terror group surrendered control of 98 percent of its territory in the region and now occupies only two percent of land near the Syrian city of Al-Shaafah, where the strike occurred.