USS Pueblo, John Anthony Walker… Walker began spying for the Soviets in 1968, when, distraught over his financial difficulties, he walked into the Soviet Embassy in Washington, D.C., sold a top secret document (a radio cipher card) for several thousand dollars, and negotiated an ongoing salary of $500 to $1,000 a week. Walker justified his treachery by claiming that the first classified Navy communications data he sold to the Soviets had already been completely compromised when the North Koreans had captured the U.S. Navy communications surveillance ship, the USS Pueblo. Yet the Koreans captured the Pueblo in January 1968 – one month after Walker had betrayed the information. Furthermore, a 2001 thesis presented at the U.S. Army Command and General Staff College using information obtained from Soviet archives and from Oleg Kalugin, indicated that the Pueblo incident may have taken place because the Soviets wanted to study equipment described in documents supplied to them by Walker.