Kaliningrad Oblast is the westernmost federal subject of the Russian Federation. It is a semi-exclave on the Baltic Sea, surrounded by Poland to the south and Lithuania to the north and east. The largest city and administrative centre is the city of Kaliningrad. The port city of Baltiysk is Russia's only port on the Baltic Sea that remains ice-free in winter. Kaliningrad Oblast had a population of roughly one million in the 2021 Russian census. It has an area of 15,125 square kilometres (5,840 sq mi).
Various peoples, including Lithuanians, Germans, and Poles, lived on the land which is now Kaliningrad. The territory was formerly the northern part of East Prussia. With the defeat of Nazi Germany in World War II, the territory was annexed to the Russian SFSR by the Soviet Union. Following the post-war migration and flight and expulsion of Germans, the territory was populated with Soviet citizens, mostly Russians.