And those conditions, it turns out, would be vastly more draconian than they are at Guantanamo Bay.

"Where demanded by justice and national security, we will seek to transfer some detainees to the same type of facilities in which we hold all manner of dangerous and violent criminals within our borders," President Obama said in a speech at the National Archives in May. "Bear in mind the following fact: Nobody has ever escaped from one of our federal supermax prisons, which hold hundreds of convicted terrorists."

Based on what is known about restrictions in the country's highest-security federal prisons, Mohammed and other terrorism suspects would face profound isolation in the United States.

If sent to a facility such as the federal supermax prison in Florence, Colo., they would be sealed off for 23 hours a day in cells with four-inch-wide windows and concrete furniture. If they behave, and are allowed an hour's exercise each day in a tiny yard, they will do so alone. They will have little or no human contact except with prison officials. And the International Committee of the Red Cross, the only outside group with access to Camp 7, will no longer have contact with them.

"You will die with a whimper," U.S. District Judge Leonie M. Brinkema told Zacarias Moussaoui, before the Sept. 11 conspirator was taken to the supermax facility in Florence to serve a life sentence. "You will never again get a chance to speak."