One of the points at issue in the speeches today of Pres. Obama and former VP Cheney is whether Guantanamo Bay, use of "enhanced interrogation techniques" and so forth have been a "recruitment tool" for jihadists. Cheney, in particular, ridiculed the idea.
Actually, no one really knows whether or to what extent Guantanamo has been a "recruitment tool," because people signing up for terrorist activity do not usually write neat little explanations of their motives. In some cases, their motives may not be entirely clear even to themselves. (How many of us understand exactly why we do what we do?) My hunch is that civilian casualties from U.S./NATO operations in Afghanistan, as well as civilian casualties in Pakistan, are more powerful "recruitment tools" than Guantanamo Bay has been.
The main case for closing Guantanamo is not that it is a recruitment tool but that holding people indefinitely or for very long periods in a kind of legal limbo violates basic principles of the American legal and constitutional order, and jettisoning those principles here is unnecessary. Practically, the situation is a "mess," as Obama said today, and cleaning it up is not going to be easy. And with Democratic senators unwilling to show political courage in this context, the problem becomes that much more difficult.