(a) Whoever, while employed by or accompanying the Federal Government outside the United States, engages in conduct outside the United States that would constitute an offense under chapter 77 or 117 of this title if the conduct had been engaged in within the United States or within the special maritime and territorial jurisdiction of the United States shall be punished as provided for that offense.

(b) No prosecution may be commenced against a person under this section if a foreign government, in accordance with jurisdiction recognized by the United States, has prosecuted or is prosecuting such person for the conduct constituting such offense, except upon the approval of the Attorney General or the Deputy Attorney General (or a person acting in either such capacity), which function of approval may not be delegated.