Washington ? The U.S. detention facility at Guantanamo Bay, Cuba, has lots of hard cases. But the hardest of them all, says President Barack Obama, will be those who cannot be put on trial or freed.

For them, the U.S. is crafting some sort of detention policy that reminds civil liberties groups of the Bush-era policies they despise.

“This is the toughest issue we face,” Obama said Thursday.

Already, the Obama administration is sorting each of the remaining 240 detainees at the Navy-run detention center in Cuba into five categories, but by far the thorniest is the group the Obama administration believes must be held without charge.

Obama said examples of such people include those who received extensive al-Qaida training, commanded Taliban troops or swore allegiance to Osama bin Laden.

“These are people who, in effect, remain at war with the United States,” the president said.

Such language suggests they could be detained in a manner similar to prisoners of war, perhaps on a military base other than Guantanamo.

But by Obama’s own terms, closing the Guantanamo detention center may mean creating a mini-Guantanamo, whether at a military base, super-secure prison or elsewhere.

The president’s speech offered a broad vision for how to close Guantanamo but not the specifics of where the detainees in this most difficult group might be kept under lock and key.

“Obama may be growing toward the Bush position on some of these detainees, and some facility like Guantanamo may have to continue for some kind of indefinite detention,” said Paul Rothstein, a Georgetown University legal ethics professor.

The Supreme Court has ruled that the detainees have some rights to challenge their detention in U.S. civilian courts, but the high court has never ordered a specific detainee released.

The president’s plans angered civil libertarians, who charge that Obama is not dismantling the anti-terror apparatus created by President George W. Bush but rebuilding a new version of it.

“The new president is looking a lot like the old,” said Shayana Kadidal, a lawyer for the Center for Constitutional Rights, which represents some of the detainees.

Also still to be decided is exactly how many detainees will be held under those conditions, and for how long.

The rest of the Guantanamo detainees will fall into four categories:

• Those who have been ordered released by U.S. judges. There are currently 21 such detainees.

• Those the Obama administration has approved for release. Obama said there are about 50. Some may be sent to foreign countries for trial, some may be released, and some may have to live with certain security conditions.

• Those who can be put on trial in U.S. civilian courts.

• Those to be tried in military commissions.