Katyn massacre, also known as the Katyn Forest massacre (Polish: zbrodnia katyńska, 'Katyń crime'), was a mass execution of Polish military officers, policemen and civilian prisoners of war ordered by Soviet authorities on March 5, 1940. The number of victims is estimated at about 22,000, with the most commonly cited number of 21,768. The victims were murdered in the Katyn forest in Russia, the Kalinin (Tver) and Kharkiv prisons and elsewhere. About 8,000 were officers taken prisoner during the 1939 Soviet invasion of Poland, the rest being Poles arrested for allegedly being "intelligence agents, gendarmes, spies, saboteurs, landowners, factory owners, lawyers, priests, and officials." Since Poland's conscription system required every unexempted university graduate to become a reserve officer, the Soviets were able to round up much of the Polish intelligentsia, and the Jewish, Ukrainian, Georgian and Belarusian intelligentsia of Polish citizenship.
Originally, "Katyn massacre" referred to the massacre at Katyn Forest, near the villages of Katyn and Gnezdovo (ca. 19 km west of Smolensk, Russia), of Polish military officers in the Kozelsk prisoner-of-war camp. It now is applied to the simultaneous executions of POWs from geographically distant Starobelsk and Ostashkov camps, and the executions of political prisoners from West Belarus and West Ukraine, shot on Stalin's orders at Katyn Forest, at the NKVD (Narodny Komissariat Vnutrennikh Del, the Soviet secret police) headquarters in Smolensk, at a Smolensk slaughterhouse, and at prisons in Kalinin (Tver), Kharkiv, Moscow, and other Soviet cities.
Nazi Germany announced the discovery of mass graves in the Katyn Forest in 1943. The revelation led to the break up of diplomatic relations between Moscow and the London-based Polish government-in-exile. The Soviet Union continued to deny the massacres until 1990, when it finally acknowledged the massacre by the NKVD, as well as the subsequent cover-up. The Russian government admitted Soviet responsibility for the massacres, yet does not classify this action as a war crime or as an act of genocide. This acknowledgement would have necessitated the prosecution of surviving perpetrators, which is what the Polish government had requested. In addition the Russian government also does not classify the dead as victims of Stalinist repression, which bars formal posthumous rehabilitation.
On 5 March 1940, pursuant to a note to Joseph Stalin from Lavrenty Beria, the members of the Soviet Politburo — Stalin, Vyacheslav Molotov, Lazar Kaganovich, Mikhail Kalinin, Kliment Voroshilov and Anastas Mikoyan; signed an order to execute 25,700 Polish "nationalists and counterrevolutionaries" kept at camps and prisons in occupied western Ukraine and Belarus. The reason for the massacre, according to historian Gerhard Weinberg, is that Stalin wanted to deprive a potential future Polish military of a large portion of its military talent: It has been suggested that the motive for this terrible step [the Katyn massacre] was to reassure the Germans as to the reality of Soviet anti-Polish policy. This explanation is completely unconvincing in view of the care with which the Soviet regime kept the massacre secret from the very German government it was supposed to impress... A more likely explanation is that... [the massacre] should be seen as looking forward to a future in which there might again be a Poland on the Soviet Union's western border. Since he intended to keep the eastern portion of the country in any case, Stalin could be certain that any revived Poland would be unfriendly. Under those circumstances, depriving it of a large proportion of its military and technical elite would make it weaker".