((a)) ** Vehicles and other instruments of international traffic except communications satellites** Vehicles and other instruments of international traffic, of any class specified by the Secretary of the Treasury, shall be excepted from the application of the customs laws to such extent and subject to such terms and conditions as may be prescribed in regulations or instructions of the Secretary of the Treasury. The authority delegated to the Secretary by this subsection shall not extend to communications satellites and components and parts thereof.
((b)) ** Rescue and relief equipment; personal property related to use of land under United States-Mexico Boundary Treaty of 1970; forfeit of articles to United States** The Secretary of the Treasury may provide by regulation or instruction for the admission, without entry and without the payment of any duty or tax imposed upon or by reason of importation, of—
((1)) aircraft, equipment, supplies, and spare parts for use in searches, rescues, investigations, repairs, and salvage in connection with accidental damage to aircraft;
((2)) fire-fighting and rescue and relief equipment and supplies for emergent temporary use in connection with conflagrations;
((3)) rescue and relief equipment and supplies for emergent temporary use in connection with floods and other disasters; and
((4)) personal property related to the use and enjoyment of a separated tract of land as described in article III of the Treaty To Resolve Pending Boundary Differences and Maintain the Rio Grande and Colorado Rivers as the International Boundary between the United States of America and the United Mexican States signed on .