It would be dangerous to release the prisoners of Guantanimo.

If there are over 700 prisoners at Guantanimo, and they are released and go back to fighting Afghani, Iraqi and American and international peacekeeping troops, they will likely be killed themselves. If they are not themselves killed, each released prisoner can kill dozens, if not hundreds of troops and innocent civilians. It's better to keep them in jail indefinitely than to release them into their societies to kill and maim. Al Qaeda has been stepping up attacks in Afghanistan. The last thing we need to do is add to their numbers.