According to Pavel Sudoplatov, NKVD officers Victor Ilyin and Mikhail Maklyarsky conceived Operation Berezino as an extension of Operation Monastyr ("Operation Monastery") (1941–1944). In 1941, NKVD operative Alexander Demyanov (Soviet codename "Heyne"), wearing a persona of a disgruntled bohemian socialite, established contact with the German resident in Moscow. The NKVD used this opportunity to expose the "Abwehr" undercover network in the Soviet Union. In December 1941, Demyanov "defected" to the Germans and showed up at the Abwehr field office in Smolensk. Three months later, he returned to Moscow as a trusted German agent. His apartment became a death trap for scores of genuine German agents, but he retained the trust of his German superiors. In the middle of 1942, Demyanov's control officer Willie Fischer expanded the operation into a strategic level disinformation campaign. For more than two years, Demyanov supplied Reinhard Gehlen, the head of the "Oberkommando des Heeres" ("OKH", German Army High Command) "Fremde Heere Ost" (Foreign Armies East) department with carefully scripted "military plans." According to Sudoplatov, the German success in repelling the Soviet Rzhev offensive were, in part, influenced by "correct" information fed to Gehlen through Demyanov. The intent of feeding the Germans information about an operation, was to conduct strategic deception to distract the Germans from the simultaneous Operation Uranus in the south. The Germans were indeed surprised by the latter attack, resulting in the encirclement and eventual surrender of the German 6th Army at Stalingrad.