Operation Osoaviakhim was a secret Soviet operation under which more than 2,500 former Nazi German specialists (scientists, engineers and technicians who worked in several areas) from companies and institutions relevant to military and economic policy in the Soviet occupation zone of Germany (SBZ) and Berlin, as well as around 4,000 more family members, totalling more than 6,000 people, were transported from former Nazi Germany as war reparations to the Soviet Union. It took place in the early morning hours of October 22, 1946 when MVD (previously NKVD) and Soviet Army units under the direction of the Soviet Military Administration in Germany (SMAD), headed by Ivan Serov, rounded up German scientists and transported them by rail to the USSR.