In general— The authorities conferred upon the President by section 5(b) of the Trading With the Enemy Act (
50 U.S.C. 4305(b)), which were being exercised with respect to Cuba on July 1, 1977, as a result of a national emergency declared by the President before that date, and are being exercised on the day before the effective date of this Act, may not be exercised on or after such effective date with respect to Cuba.