23 CFR 771.137: International actions.

(a) If the Administration determines a major Federal action is proposed, the requirements of this part apply to:

(1) Administration actions significantly affecting the environment of a foreign nation not participating in the action or not otherwise involved in the action.

(2) Administration actions outside the U.S., its territories, and possessions that significantly affect natural resources of global importance designated for protection by the President or by international agreement.

(b) If communication with a foreign government concerning environmental studies or documentation is anticipated, the Administration must coordinate such communication with the Department of State through the Office of the Secretary of Transportation.