It was Fuller’s visits to the Soviet Union that recaptured the interest of the FBI in the mid-1960s. He visited St. Petersburg in August of 1964, then met with President Lyndon Johnson at the White House only months later.

By 1965, the FBI was discussing how to interview Fuller without “divulging knowledge of his association with Soviet nationals,” documents show.

It was in the middle of the Cold War, and the fear of spies and subversives cast a pall of suspicion on any contact with the Soviet Union.

When agents finally interviewed Bucky at his home in Carbondale, it appears he assuaged their concerns about his Russian contacts.

He was forthcoming about his meetings with Soviet officials at conferences and symposiums around the world, and assured the agents he had “never been approached by anyone from the USSR or any other country to divulge anything concerning the work performed by him for the United States Government,” the report reads.

He admitted contact with the subjects of other FBI investigations, whose names appear redacted in the reports. In one case, a meeting with a Russian subject was only “playing politics,” Fuller said, to gain support for his work.