The U.S. Treasury Department has the the authority to cut a bank loose from the from the U.S. financial system as a result of the Patriot Act passed after 9/11. Actually, I think they always had the authority, but implementation used to be more complicated. This is what has happened to BDA. IMO, it's only natural that the U.S. Treasury exercises authority over U.S. dollar accounts where ever they might be located. Otherwise, any overseas bank could just create U.S. dollar accounts out of funny money deposits. I know that China regulations concerning yuan accounts overseas, so its not only the U.S. that does this. The counterfeit North Korean notes used to be called "superbills," but there is now readily available technology to detect them. If BDA was fooled, it's because they didn't want to know.