On March 5, 1940, the Soviet Union decided to shoot Polish prisoners of war in the largest camps at Kozelsk (Optina Monastery), Ostashkov (Stolobny Island on Lake Seliger near Ostashkov) and Starobelsk. A series of mass executions of about 22,000 Polish military officers and intelligentsia was carried out by the Union, specifically the NKVD (“People’s Commissariat for Internal Affairs”, the Soviet secret police) in April and May 1940.
The prisoners had been detained by the NKVD in the pre-WWII eastern provinces of the Republic of Poland.
In the years 1940-1990, the USSR authorities denied their responsibility for the Katyń massacre. On April 13, 1990, they officially acknowledged that it was “one of the gravest crimes during Stalinism”. Many issues related to the massacre have not yet been clarified.
(PAP)