But they cannot be allowed to enter the United States, either, because that would set a bad legal precedent. A U.S. federal court judge "ruled that they were being held illegally, but he said he was powerless to order their release." The Supreme Court has declined to hear the detainees' appeal, but on May 8 an appeals court panel will determine whether federal judges have any power to intervene.
So they remain imprisoned indefinitely at Guantánamo Bay.
(More detail at Sheldon Richman's Free Association blog.)