The German rocket center in Peenemünde was located in the eastern part of Germany, which became the Soviet zone of occupation. On Stalin's orders, the Soviet Union sent its best rocket engineers to this region to see what they could salvage for future weapons systems. The Soviet rocket engineers were led by Sergei Korolev. He had been involved in space clubs and early Soviet rocket design in the 1930s, but was arrested in 1938 during Joseph Stalin's Great Purge and imprisoned for six years in Siberia. After the war, he became the USSR's chief rocket and spacecraft engineer, essentially the Soviet counterpart to von Braun. His identity was kept a state secret throughout the Cold War, and he was identified publicly only as "the Chief Designer." In the West, his name was only officially revealed when he died in 1966.