NATO leaders are meeting in Madrid amid what Secretary General Jens Stoltenberg calls “the most serious security crisis we have faced since the Second World War.”
Moscow's move came days after Finland announced it wanted to join NATO and amid its refusal to pay for the gas in rubles.
Finland is the latest country to lose the energy supply, which is used to generate electricity and power industry, after rejecting Russia’s decree.
Approval usually takes eight to 12 months, but NATO wants to move quickly given the threat from Russia hanging over the Nordic countries’ heads.
Nearly three months have passed since Russia invaded Ukraine.
Sweden, also nonaligned, moved a step closer to applying for NATO membership after the governing Social Democratic party met Sunday and backed joining the trans-Atlantic alliance.
The Kremlin warned it may take retaliatory “military-technical” steps after Finland’s leaders said they favor joining NATO.
The nation's president and prime minister announced that Finland should apply right away for to join the military defense pact founded in part to counter the Soviet Union.
Russia's invasion of Ukraine has also prompted a rethink of staunch military neutrality by Sweden.
The announcement paves the way for the alliance to expand amid Russia's war in Ukraine.