Russian President Vladimir Putin has denied the Kremlin is threatened by Finland and Sweden joining NATO, but nonetheless said Russia would take military countermeasures.
"There is nothing to worry us in terms of Swedish and Finnish membership of NATO," Putin said in comments to journalists during a visit to Turkmenistan, adding that both countries should be prepared for a Russian reaction all the same.
"They must clearly understand that previously there were no threats to them - but if troops are stationed there and infrastructure established, we will have to respond accordingly and make the same threats to the territory from where threats to us are coming," he said, according to the Russian TASS news agency.
"Everything was good between us, but now there will be some tension - that is obvious, there is no doubt about it, it can't go any other way," Putin continued.
Russia had already threatened consequences after learning of initial Finnish and Swedish plans to join NATO.
The two countries decided to abandon decades of neutrality and join the defence alliance in the wake of Russia's invasion of Ukraine.
The membership process was initiated at the NATO summit in Madrid on Wednesday.
The expansion of the defence alliance will extend its land border with Russia by more than 1,300 kilometres.
Putin stressed that Finland and Sweden joining NATO would be quite different to Ukraine being granted membership, and denied that Russia had triggered Finland and Sweden's volte-face on NATO membership through its vehement opposition to Ukraine's own plans to join the alliance.
Putin accused the West of trying to turn Ukraine into an "anti-Russia" that it would use to destabilize Russia and attack its culture. That would not be the case with Finland and Sweden, he added.