Kaliningrad Oblast is the westernmost federal subject of the Russian Federation, in Central and Eastern Europe. It is a semi-exclave situated on the Baltic Sea. The oblast is surrounded by two European Union and NATO members: Poland to the south and Lithuania to the north and east. The largest city and administrative centre of the province (oblast) is the city of Kaliningrad, formerly known as Königsberg. 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 1 million in the Russian Census of 2021.

An enclave is a territory that is entirely surrounded by the territory of only one other state or entity. Such territory can be a small territory as part of a larger one. Enclaves may also exist within territorial waters. Enclave is sometimes used improperly to denote a territory that is only partly surrounded by another state. Many enclaves are also exclaves, but some are not, for example Vatican City and San Marino and Lesotho are completely enclaved sovereign states.