Canadian Omar Khadr was accused of killing a US soldier
The Pentagon is to ask US military judges to reconsider a decision earlier this week to throw out charges against two Guantanamo Bay detainees.
This week charges against Canadian Omar Khadr and Yemeni Salim Ahmed Hamdan, were dropped, casting fresh doubt on efforts to try foreign terror suspects.
Both cases collapsed because military authorities had failed to designate the men as "unlawful" enemy combatants.
The Pentagon will be filing a motion for reconsideration, a spokesman said.
Salim Ahmed Hamdan has been accused of being al-Qaeda leader Osama Bin Laden's driver and bodyguard.
Canadian Omar Khadr was accused of killing a US soldier in Afghanistan with a grenade.