Moscow has accused NATO of threatening Russia’s "security and national interests" by officially welcoming Finland into the alliance at a ceremony in Brussels later Tuesday.
Kremlin spokesman Dmitry Peskov told journalists that Finland’s accession is an "aggravation of the situation," referring to Moscow’s claims that the military alliance is planning to encroach on Russia’s borders.
Finland shares an 800-mile (1,300-kilometer) border with Russia, but NATO Secretary General Jens Stoltenberg told reporters earlier that the alliance's troops would only be stationed in Finland with the country’s consent.
The move, Peskov warned, will force Moscow to "take counter-measures to ensure our own security, both tactically and strategically."
He said Moscow would "keep monitoring the situation and the deployment of NATO infrastructure and weapons on the territory of Finland," adding the "response measures will be taken accordingly."
While Russia’s premise for its invasion of Ukraine was in part to fend off NATO from expanding close to its borders, Peskov rejected claims that Finland’s accession, a direct response to the war, was a geopolitical defeat for Russian President Vladimir Putin, claiming it is "fundamentally different" from the situation with Ukraine.