Poland–Russia border

The modern Poland–Russia border is a nearly straight-line division between the Republic of Poland (European Union (EU) member) and the Russian Federation (CIS member) exclave of Kaliningrad Oblast. It is currently 232 kilometres (144 mi) long. Its current location and size were decided as part of the aftermath of World War II. In 2004 it became part of the boundary of the EU and Commonwealth of Independent States.

The history of the border between Poland and Russia can be traced to the early history of both nations, with one of the earliest notable incidents being the Polish king Boleslaw I's intervention in the Kievan succession crisis, 1018. Following the formation of the Polish-Lithuanian Commonwealth, Poland's eastern border, most of it with the Tsardom of Muscovy (later, the Russian Empire), stretched from the Baltic Sea in the north to the Black Sea in the south. During the period of partitions of Poland, which shifted the Russian borders some 300 miles (480 km) west, several small Polish statelets such as the Duchy of Warsaw and the Congress Kingdom shared a border with the Russian Empire. Following World War I, the new Second Polish Republic shared a border with the Soviet Union (USSR), shaped during the Polish-Soviet War, and confirmed at the Treaty of Riga at the line Dzisna-Dokshytsy-Słucz-Korets-Ostroh-Zbrucz. That border was 1,407 kilometres (874 mi) long. Following World War II, the new border (see territorial changes of Poland immediately after World War II) was drawn between the People's Republic of Poland and the USSR. The new Polish-Soviet border was 1,321 kilometres (821 mi) long at first, and subject to a minor modification in the 1951 Polish–Soviet territorial exchange, which reduced the border length to 1,244 kilometres (773 mi).