John Anthony Walker

John Anthony Walker Jr. (July 28, 1937 – August 28, 2014) was a United States Navy chief warrant officer and communications specialist convicted of spying for the Soviet Union from 1967 to 1985 and sentenced to life in prison.

In late 1985, Walker made a plea bargain with federal prosecutors, which required him to provide full details of his espionage activities and testify against his co-conspirator, former senior chief petty officer Jerry Whitworth. In exchange, prosecutors agreed to a lesser sentence for Walker's son, former Seaman Michael Walker, who was also involved in the spy ring. During his time as a Soviet spy, Walker helped the Soviets decipher more than one million encrypted naval messages, organizing a spy operation that The New York Times reported in 1987 "is sometimes described as the most damaging Soviet spy ring in history."

After Walker's arrest, Caspar Weinberger, President Ronald Reagan's Secretary of Defense, concluded that the Soviet Union made significant gains in naval warfare attributable to Walker's spying. Weinberger stated that the information Walker gave Moscow allowed the Soviets "access to weapons and sensor data and naval tactics, terrorist threats, and surface, submarine, and airborne training, readiness and tactics."

In the June 2010 issue of Naval History Magazine, John Prados, a senior fellow with the National Security Archive in Washington, D.C., pointed out that after Walker introduced himself to Soviet officials, North Korean forces seized USS Pueblo in order to make better use of Walker's spying. Prados added that North Korea subsequently shared information gleaned from the spy ship with the Soviets, enabling them to build replicas and gain access to the U.S. naval communications system, which continued until the system was completely revamped in the late 1980s. It has emerged in recent years that North Korea acted alone and the incident actually harmed North Korea's relations with most of the Eastern Bloc.