Asset blocking— The exercise of all powers granted to the President by the International Emergency Economic Powers Act (
50 U.S.C. 1701 et seq.) to the extent necessary to block and prohibit all transactions in all property and interests in property of a person determined by the President to be subject to subsection (a) if such property and interests in property are in the United States, come within the United States, or are or come within the possession or control of a United States person.