Sorry.... Guantanamo Bay Naval Base is not U.S. territory.
"U.S. territory" means land owned by the U.S. and the land that Guantanamo Naval Base is on is legally owned by Cuba.
A judge may have ruled that Guantanamo may constitute some sort of U.S. control but Guantanamo is Cuban territory perpetually leased to the U.S. in a lease agreement that states that the lease may not be terminated except by the mutual agreement of both parties.
The yearly "rent" set forth by treaty for the Guantanamo Naval Base land was $2000 in gold.
The U.S. now sends a yearly check for $4,085 to Havana and Castro has refused to cash those checks since 1959.
I spent one year stationed in Guantanamo. If a U.S. civilian contract worker committed a crime, they had to be sent back to the U.S. for trial as no civilian U.S. Court existed on Guantanamo.
What matters is that foreign terrorists have just summarily been many of the same rights that only US citizens had before.