The Common Dreams newswire reports that seven members of a group called "Witness Against Torture" have been served papers by the Treasury Department's Office of Foreign Assets Control (OFAC) for attempting to visit prisoners at the U.S. Naval Base at Guantanamo Bay.
I suspect the OFAC is concerned that the group might have taken small amounts American currency to the Island of Cuba. What if they gave some to the prisoners at Guantanamo? Those prisoners were allegedly connected with Saddam Hussein's desire to acquire weapons of mass destruction. Since we launched our pre-emptive strike on Iraq, the whole world knows what happens to anyone who even think about wanting WMD's.
It's perfectly understandable why America can't let any of its currency fall into the wrong hands. We've had proof since the 1960's that Fidel Castro wanted to acquire WMD's and the missiles to deliver it.