A federal judge on Thursday ordered the release of a detainee at the U.S. military prison at Guantanamo Bay, Cuba, who was accused of attacking U.S. troops with a grenade in 2002.

The government will have at least until Aug. 21 to send the detainee back to Afghanistan or it could seek criminal charges against him in the attack. In a court filing last week, the Justice Department said it was mulling such a prosecution.

Mohammed Jawad, whose case has generated intense support from human rights groups, might have been as young as 12 when he was arrested by Afghan authorities and turned over to the U.S. military.

He has challenged his confinement in a federal lawsuit being heard by U.S. District Judge Ellen S. Huvelle under habeas corpus, a legal doctrine that allows prisoners to contest their confinements before independent arbiters.