The Greek Operation (Russian: Греческая Операция, translit. Grecheskaya Operatsiya; Ukrainian: Грецька операція) was an organised mass persecution of the Greeks of the Soviet Union that was ordered by Soviet leader Joseph Stalin. Greeks often use the term "pogrom" (πογκρόμ) for this persecution, though this term usually refers to mob violence rather than persecution by police acting under direct orders, as this one was. It began on December 15, 1937, and marked the beginning of the repressions against Greeks that went on for 13 years. Depending on the sources, it is estimated that between 20,000 and 50,000 Greeks died by the end of this campaign.