19 U.S.C. § 1309: Supplies for certain vessels and aircraft

for supplies (not including equipment) of (A) vessels or aircraft operated by the United States, (B) vessels of the United States employed in the fisheries or in the whaling business, or actually engaged in foreign trade or trade between the Atlantic and Pacific ports of the United States or between the United States and any of its possessions, or between Hawaii and any other part of the United States, or between Alaska and any other part of the United States, or (C) aircraft registered in the United States and actually engaged in foreign trade or trade between the United States and any of its possessions, or between Hawaii and any other part of the United States or between Alaska and any other part of the United States; or for supplies (including equipment) or repair of (A) vessels of war of any foreign nation, or (B) foreign vessels employed in the fisheries or in the whaling business, or actually engaged in foreign trade or trade between the United States and any of its possessions, or between Hawaii and any other part of the United States or between Alaska and any other part of the United States, where such trade by foreign vessels is permitted; or for supplies (including equipment), ground equipment, maintenance, or repair of aircraft registered in any foreign country and actually engaged in foreign trade or trade between the United States and any of its possessions, or between Hawaii and any other part of the United States or between Alaska and any other part of the United States, where trade by foreign aircraft is permitted. With respect to articles for ground equipment, the exemption hereunder shall apply only to duties and to taxes imposed upon or by reason of importation. Articles withdrawn from bonded warehouses, bonded manufacturing warehouses, continuous customs custody elsewhere than in a bonded warehouse, or from a foreign-trade zone, imported articles, and articles of domestic manufacture or production, laden as supplies upon any such vessel or aircraft of the United States or laden as supplies (including equipment) upon, or used in the maintenance or repair of, any such foreign vessel or aircraft, shall be considered to be exported within the meaning of the drawback provisions of this chapter. Any article exempted from duty or tax, or in respect of which drawback has been allowed, under this section or section 1317 of this title and thereafter removed in the United States from any vessel or aircraft, or otherwise returned to the United States, shall be treated as an importation from a foreign country. The privileges granted by this section and section 1317 of this title in respect of aircraft registered in a foreign country shall be allowed only if the Secretary of the Treasury shall have been advised by the Secretary of Commerce that he has found that such foreign country allows, or will allow, substantially reciprocal privileges in respect of aircraft registered in the United States. If the Secretary of Commerce shall advise the Secretary of the Treasury that he has found that a foreign country has discontinued, or will discontinue, the allowance of such privileges, the privileges granted by this section and such section 1317 shall not apply thereafter in respect of aircraft registered in that foreign country. claims filed or liquidated on or after January 1, 1988 , and claims that are unliquidated, under protest, or in litigation on the date of enactment of this Act [ Aug. 20, 1990 ].”