Canadian citizen OmarKhadr, now 23, is accused of throwing a grenade that killed a US soldier during a gun battle in Afghanistan in 2002, when he was 15.
The other two, OmarKhadr, a Canadian accused of killing an American soldier in Afghanistan, and Salim Ahmed Hamdan, Osama bin Laden's former Yemeni driver, are likely to go on trial later this summer.
OmarKhadr, a Canadian citizen charged with the death of Army Sergeant First Class Christopher Speer in Afghanistan by tossing a hand grenade in a July 2002 fire fight, has been controversial since his capture.