Adolf Georgievich Tolkachev (Russian: Адольф Георгиевич Толкачёв; 1927 in Aktyubinsk, Kazakhstan – September 24, 1986) was a Soviet Union electronics engineer who provided key documents to the United States Central Intelligence Agency (CIA) between 1979 and 1985. Working at the Soviet radar design house Phazotron as one of the chief designers, Tolkachev gave the CIA complete detailed information about such projects as the R-23, R-24, R-33, R-27, and R-60, S-300; fighter-interceptor aircraft radars used on the MiG-29, MiG-31, and Su-27; and other avionics. Among the equipment compromised by Tolkachev was the passive phased array radar used by the MiG-31 Foxhound fighter, which the U.S. considered the most advanced airborne radar. He was executed as a spy in 1986. Wikipedia
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