President Vladimir Putin has indicated that Russia would move troops toward its border with Finland if the Nordic country became a member of NATO, whose eastward expansion since the fall of the Soviet Union has long angered the Kremlin.
"Finnish forces would cease being independent, cease being sovereign in the full sense of that word," Putin said after a July 1 meeting in Finland with President Sauli Niinisto. "They would become part of NATO's military infrastructure, which overnight would be at the borders of the Russian Federation."
Putin added: "Do you think that we will continue as before by keeping our troops 1,500 [kilometers] away?"
His comments came ahead of next week's NATO summit in Warsaw that Niinisto has been invited to attend.
Alliance members are expected to endorse a larger deployment of alliance military forces to Eastern Europe.
NATO says the planned increase of forces on its eastern flank is in response to Russian aggression in Eastern Europe, including its 2014 seizure and annexation of Ukraine's Crimean Peninsula and the ongoing war between Russia-backed separatists and Kyiv's military in eastern Ukraine.
Finland has said it will continue to participate in NATO exercises and decide for itself whether or not to join the alliance.