The Soviet Union and the United States spent most of the Cold War trying to beat one another in a nuclear race. As a result, the KGB constantly tried to steal U.S. secrets, and the U.S. federal agencies were constantly blocking them.
After World War II, to create stability amongst the world powers, the United Nations was founded with a headquarters in New York City. Unfortunately, while the gesture was supposed to bring the nations together, some of the other countries only pretended to play by the rules.
Often, they had their spies working to gather intel while the diplomats played nice. Since countries like Russia had a two-faced nature, the FBI needed to be on top of their counterintelligence game.
In April of 1977, the FBI asked Navy Lt. Commander Arthur Lindberg to join a counterintelligence mission. The FBI thought the Soviets were recruiting spies on cruise ships and using their office in the U.N. to operate espionage missions.
A double agent mission seemed like the best way to get the intel they needed, but the KGB was on high alert. Lindberg was the perfect option. He was close to retirement, needed money, and was high ranking.
Lindberg agreed, and Operation Lemonade began with him purchasing a ticket for a cruise on the MS Kazakhstan. Before leaving the ship, he gave a crew member a note for the Russian ambassador stating that he would sell them military information if they gave him money toward retiring.
On August 30, 1977, the Soviets reached out and gave Lindberg the code name Ed and his contact was Jim. An in-person meeting was set up for September 24, 1977.
The Naval Investigative Agent working the Lindberg, Terry Tate, had nuclear documents declassified so Lindberg could give them to the Soviets. Lindberg used dead drops to give them the intel on October 22, 1977.
The FBI surveilled the drops, eventually tracing the spy who picked the intel up, Rudolf Chernyayev. Finally, on March 12, 1978, the FBI had plenty of evidence for a warrant. The spies, Valdik Enger, Rudolf Chernyayev, and Vladimir Zinyakin, were arrested on May 20, 1978.
One, Zinyakin, had diplomatic immunity and was deported. The rest were sentenced to 50 years in prison for espionage. But they were eventually exchanged for five Soviet dissidents.