41 C.F.R. § 102-117.40

Federal law requires using U.S. flag carriers for international air and ocean shipments. Key statutes include:

(a) Fly America Act (49 U.S.C. 40118)—requires use of U.S. air carriers when available.

(b) Cargo Preference Act (46 U.S.C. 55305)—requires that at least 50% of U.S. Government-impelled ocean cargo be transported on U.S. flag vessels.