Washington (CNN) The Defense Department intends to release an American citizen accused of fighting for ISIS, according to a Justice Department filing Wednesday night.

The unnamed individual has been detained as an enemy combatant in Iraq since September. He was turned over to American forces by a US-backed militia fighting ISIS in Syria.

The Justice Department said the US plans to release the dual US-Saudi national in a town in Syria, the name of which was not provided, no sooner than 72 hours from the time of the filing. The department notified the American Civil Liberties Union, which represents the man, of its intent and the man "would not agree to the release" as described, the government wrote.

"Accordingly, out of an abundance of caution, the Department is filing this Notice of its intent to release Petitioner in the town specified in the Declaration," the filing says.

The move comes as a federal judge in DC mulled an ACLU challenge to the man's detention, which had drawn unprecedented judicial scrutiny to the US's legal underpinning for the war on ISIS. If the release is allowed to go through, it would render the challenge essentially moot.

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