Russia has warned NATO that it could resort to nuclear weapons if the alliance attempts to cut Kaliningrad off from the rest of Russian territory.

In a diplomatic document sent to NATO, Moscow warned that any attempt to isolate the Russian exclave could trigger a direct military confrontation and carry the risk of severe escalation.

Kaliningrad is a Russian territory on the Baltic Sea, located between NATO members Poland and Lithuania and separated from mainland Russia.

Russian officials have repeatedly identified the defense of Kaliningrad as a major security priority, while NATO countries have strengthened their military presence in the Baltic region since Russia’s invasion of Ukraine.

The latest warning represents a sharp escalation in Moscow’s rhetoric over the strategically important territory and raises concerns over the potential for a wider Russia-NATO confrontation.

Moscow has warned that any conflict involving Kaliningrad could carry consequences extending to the nuclear level.