49 C.F.R. § 30.5
The provisions of section 109(a) of the Continuing Resolution apply to contracts (or new subcontracts under existing contracts, whether or not subject to the restriction) entered into after December 22, 1987, its date of enactment, and before October 1, 1988. The provisions of section 115 of the Airport Safety Act apply to contracts funded by the Act and entered into after December 30, 1987, its date of enactment; the restrictions remain effective so long as money provided by the Airport Safety Act is used. Accordingly, any contracts or subcontracts subject to the restrictions of this part entered into with contractors or subcontractors owned or controlled by citizens of subject countries, as defined by §§ 30.7 and 30.9 of this part, since December 22, 1987 shall be canceled at no cost to the Government, subject to the waiver provisions of § 30.17 of this part. All public works or public buildings contracts entered into after December 22, 1987, shall include, or be modified to include, a provision prohibiting subcontracting with citizens of subject countries, as defined by §§ 30.7 and 30.9 of this part.
49 C.F.R. §30.5