John McCain actually said...

I would not want to do anything in extending or amending the AUMF that makes it easier to keep Guantanamo open.

there are more legal constraints because it does not require congressional approval

I think it is fair to say that Guantanamo at this stage is an unmitigated disaster for the United States.

the President clearly has the inherent authority to use force if necessary to protect the United States against a specific imminent threat