English: A map of the camp for Polish prisoners of war held by the Soviet intelligence bureau or NKVD in Starobielsk (nowadays in Ukraine). The PoWs were regular army officers and reserve officers who had been taken captive by the Soviet Union after its attack on Poland on 17 September 1939. The Starobielsk Camp was only one of several such camps for Polish PoWs (the main two other camps being at Kozielsk and Ostashkov). This Soviet operation was aimed at annihilating not only the Polish army but the Polish intelligentsia and was organised alongside measure taken with the same aim by the Soviet ally at that time, Hiter's Nazi Germany. The PoWs from Starobielsk, nearly 3.800 people, were murdered by the NKVD in April and May 1940 in nearby Kharkiv as part of what is collectively known as the Katyń Massacre. Altogether, nearly 22 thousand Poles are its victims.