Operation Lemon Aid-- an induced double agent operation-- was conceived, controlled, and concluded as a cooperative counterintelligence effort by the FBI and U.S. Naval Investigative Service (NIS). Two Soviet employees of the UN Secretariat, Valdik Enger and Rudolf Chernyayev, were arrested for accepting classified information from Navy Lieutenant Commander Art Lindberg, who was acting as a double agent for the United States. In 1978, Enger and Chernyayev were convicted of espionage and sentenced to 50 years in prison.
In 1977, U.S. Navy lieutenant commander/double agent Arthur Lindberg worked with the FBI to uncover Soviet spies.