The order to close the Guantanamo Bay terrorist prison, and try the inmates in the United States, under civilian legal procedures, is looming as an intelligence nightmare, and certain to increase terrorist activity. The main problem is that many terrorists have not got enough evidence against them to obtain a conviction in a conventional court. This is not unique to the current situation, but has been the case in many past counter-terrorism campaigns. Special courts had to be set up to deal with the problem, much to the chagrin of those who believe that a legal system designed for common criminals is adequate for determined fanatics. Terrorists enjoy public trials. It gives them a forum to discuss their homicidal beliefs before a large, global, audience.
In a war against religious fanatics, you want to kill or capture the leadership, and keep the live ones locked away for a long time. Some Moslem countries attempt to reason with terrorists, using religious leaders and scholars to instruct the misguided on why terrorism is unIslamic and wrong. Saudi Arabia does this, with some success. But one of the terrorists (Said Ali al Shihri) that was released from Guantanamo (505 of 775 sent there have been let go so far) went back to Saudi Arabia, was held, and "reeducated" by the Saudis for a while, then released. He has since shown up as the second in command for al Qaeda in Yemen. At least 3-4 percent of those released from Guantanamo have later shown up engaged in terrorism.
Moreover, many of the Guantanamo prisoners, if released, have no place to go. No country will accept them. Do you turn them loose in the United States? These guys would love that. Even if you put them under 24/7 surveillance (very expensive), the tail is simply seen as a challenge to the terrorists, who already know how easy it is to disappear in the United States. Even when you are being watched.
Even if there is available evidence to convict a terrorist in a conventional court, the rules-of-evidence (which allow the accused to scrutinize the evidence) puts the sources and methods of that evidence at risk of becoming known to the terrorists. This makes it easier for other terrorists to evade capture, and enables them to identify and kill those who assisted in the capture of terrorists being tried in the United States.
This process also brings politicians and lawyers into the intelligence collection process, something that makes counter-terror efforts more difficult. For example, as with police investigations of criminals, collecting intelligence on terrorists often means dealing with some unsavory people. This is political dynamite, because the mass media likes to portray this as somehow unethical. This is never an issue when common criminals are sought as sources of evidence, or even witnesses to crimes. But when terrorism is involved, it becomes an issue. Government bureaucrats tend to respond by installing more lawyers to supervise the intelligence collection effort. This, in turn, persuades the intelligence bureaucrats to order their field operatives to simply stay away from any source that might later prove embarrassing. That results in much less intelligence, fewer captured terrorists, and more terrorist attacks. If that leads to a large loss of American life, the restrictions are quietly lifted, and the field operatives are instructed to go Jack Bauer on the bad guys until the problem is dealt with. Then the cycle begins again. This has been going on for decades since the end of World War II.
Americans take for granted that there has been no Islamic terrorist attacks in the United States since September 11, 2001, and fewer elsewhere in the world. The counter-terrorism efforts in Iraq and Afghanistan are, in turn, blamed for somehow making the situation worse. In reality (which is not always a factor in forming public opinion), operations in Iraq and Afghanistan have crippled the al Qaeda, the Taliban and many other Islamic radical organizations. But many people don't want to believe it, unless something blows up near them. That's a reality check. Normally, however, reality is not the goal. Other agendas (partisan politics, religion or political correctness in general) are.