Obama and Guantanamo

The AP has a puzzling story, Obama criticizes some Guantanamo release decisions. It states, "Obama says in a broadcast interview that some of the people released from the facility in Cuba have rejoined terrorist groups. He also says U.S. officials have not always been effective in determining which prisoners will be a danger once they are let go."

But who decided to close Guantanamo? And, while I doubt Obama has the time to comb through the list of detainees, does the buck fall somewhere within his Administration?