Finland's NATO membership intensifies Russia's isolation.

Finland's admission to NATO extends the alliance's land border with Russia and further isolates Kaliningrad, an important Russian exclave on the Baltic Sea. Kaliningrad is a major military outpost, hosting Russia's Baltic Fleet and other forces, and has been called an "unsinkable aircraft carrier" that allows Moscow to project power deep into NATO and EU territory. The addition of Finland to NATO also limits Russian maritime transit and complicates efforts to resupply or reinforce Kaliningrad by sea. The possible addition of Sweden to NATO would further isolate Kaliningrad and bolster perceptions of the Baltic Sea as a "NATO lake."