The Katyñ Forest massacre, 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. Nazi Germany announced the discovery of mass graves in the Katyn Forest in 1943. 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.