The President may waive the application of the provisions of title III of the Act of March 3, 1933 (
41 U.S.C.
10a et seq.), popularly referred to as the Buy American Act, in the case of any procurement of civil aircraft and related articles of a country or instrumentality which is a party to the Agreement on Trade in Civil Aircraft referred to in section
2503
(c) of this title and approved under section
2503
(a) of this title. The President may modify or withdraw any waiver granted pursuant to this section.