The K1 Air Base is the third site coalition forces have left this month in line with US plans to consolidate its troops in two locations in Iraq.



A rocket attack on the K1 air base in late December killed an American contractor, leading to a series of tit-for-tat attacks between the US and Iran-backed Iraqi militia groups.



The attacks culminated in the US-directed killing of top Iranian general Qasem Soleimani and senior Iraqi militia leader Abu Mahdi al-Muhandis.



Coalition forces handed over the base in the northern Iraqi province of Kirkuk to Iraq's military, according to a coalition statement. At least $1.1 million of equipment was transferred to the Iraqis as 300 coalition personnel departed.



K1 has hosted coalition forces since 2017 to launch operations against the Islamic State group in the nearby mountainous areas. Areas south of Kirkuk, and north of neighboring provinces of Diyala, Salahaddin and Nineveh remain hot beds of IS activity.



The stretch of territory is also disputed between the federal Iraqi government and the autonomous Kurdish region, which has created security gaps benefiting IS militants. The coalition's presence had at times been a mediating presence between the two competing authorities.



A senior coalition official earlier this month claimed IS forces weren't as able to exploit the "security gap" between Iraqi and Kurdish forces as the militants did in the past.



"That doesn't necessarily mean that Daesh is free to operate in the way that they wish," said the official, using the Arabic acronym for the IS group. "They're still pretty constrained."



US-led forces have already withdrawn this month from Qaim, near the border with Syria, as well as the Qayara base in Nineveh. All were in line with plans to pullout from bases across Iraq and consolidate coalition forces in Baghdad and at Ain al-Asad Air Base in the country's western desert.



The plan has been in the works since late last year, the senior coalition military official said, and accelerated when Iraqi forces proved they were capable of facing the threat from the IS with limited coalition assistance.



Coalition officials said they would still assist Iraqi forces with air support and surveillance, but significantly cut back on training and ground operations, as the limited withdrawal continues.



Until last month, there were some 7,500 coalition troops based in Iraq, including 5,000 U.S. forces.



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