Story highlights It appeared that the American citizen surrendered to Kurdish elements of the Syrian Democratic Forces

This isn't the first US citizen fighting for ISIS to be detained by US allies in the region

(CNN) The US military has detained a US citizen who had been fighting with ISIS in Syria, a Pentagon spokesman confirmed to CNN Thursday.

"Syrian Democratic Forces turned over to US forces an American citizen who surrendered to the SDF on or around September 12," US Marine Corps Major Adrian Rankine-Galloway told CNN, referring to the US-backed Kurdish led group fighting ISIS in Syria.

"The US citizen is being legally detained by Department of Defense personnel as a known enemy combatant," he added.

Rankine-Galloway referred CNN to the Department of Justice for additional information.

The Department of Justice and the FBI declined to comment.

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