The Katyn massacre (Polish: zbrodnia katyńska, "Katyń crime"; Russian: Катынская резня Katynskaya reznya, "Katyn massacre", or Russian: Катынский расстрел, "Katyn execution by shooting" ) was a series of mass executions of Polish military officers and intelligentsia carried out by the Soviet Union, specifically the NKVD ("People's Commissariat for Internal Affairs", aka the Soviet secret police) in April and May 1940. Though the killings took place at several places, the massacre is named after the Katyn Forest, where some of the mass graves were first discovered.Katyn massacrePart of the aftermath of the Soviet invasion of Poland (during World War II) and Soviet repressions of Polish citizens (1939–1946)Trzy krzyze.jpgKatyn-Kharkiv-Mednoye memorial in Świętokrzyskie Mountains, PolandKatyn massacre is located in USSRKatyn massacreLocationKatyn Forest, Kalinin and Kharkiv prisons in Soviet UnionDateApril–May 1940Attack typeMass murderDeaths22,000VictimsPolesPerpetratorsSoviet Union (NKVD)Map of the sites related to the Katyn massacreMap of the sites related to the Katyn massacreThe massacre was prompted by NKVD chief Lavrentiy Beria's proposal to execute all captive members of the Polish officer corps, dated 5 March 1940, approved by the Politburo of the Communist Party of the Soviet Union, including its leader, Joseph Stalin. The number of victims is estimated at about 22,000