50 U.S.C. § 851

Except as provided in section 852 of this title , every person who has knowledge of, or has received instruction or assignment in, the espionage, counter-espionage, or sabotage service or tactics of a government of a foreign country or of a foreign political party, shall register with the Attorney General by filing with the Attorney General a registration statement in duplicate, under oath, prepared and filed in such manner and form, and containing such statements, information, or documents pertinent to the purposes and objectives of this subchapter as the Attorney General, having due regard for the national security and the public interest, by regulations prescribes.