Prohibits: (1) the authorization of funds for the U.S. assessed or voluntary contribution to the United Nations; (2) the authorization of funds for any U.S. contribution to any U.N. military operation; and (3) the expenditure of funds to support the participation of U.S. Armed Forces as part of any U.N. military or peacekeeping operation. Bars U.S. Armed Forces from serving under U.N. command.