The incorporation of the Königsberg area of East Prussia to Russia became a stated war aim of the Soviet Union at Tehran Conference in December 1943 . In 1945 , at the end of World War II , the city was captured by the Soviet Union ( see Battle of Königsberg ) . As agreed by the Allies at the Potsdam Conference , northern Prussia , including Königsberg , was given to the USSR . The western parts of Prussia were transferred to Poland . In 1946 the city of Königsberg was changed to Kaliningrad
Potsdam Conference
Potsdam Conference
Kaliningrad question