((a)) The provisions of this chapter relating to the surrender of persons who have committed crimes in foreign countries shall continue in force only during the existence of any treaty of extradition with such foreign government.

((b)) The provisions of this chapter shall be construed to permit, in the exercise of comity, the surrender of persons, other than citizens, nationals, or permanent residents of the United States, who have committed crimes of violence against nationals of the United States in foreign countries without regard to the existence of any treaty of extradition with such foreign government if the Attorney General certifies, in writing, that—

((1)) evidence has been presented by the foreign government that indicates that had the offenses been committed in the United States, they would constitute crimes of violence as defined under ; and

((2)) the offenses charged are not of a political nature.

((c)) As used in this section, the term “national of the United States” has the meaning given such term in section 101(a)(22) of the Immigration and Nationality Act ().