Nordic country that shares 800-mile border with Russia looks to end decades of non-alignment

• Russia-Ukraine war: latest updates

Finland has formally confirmed it intends to join Nato, abandoning decades of military non-alignment in a historic policy shift triggered by Russia’s invasion of Ukraine.

“The president and the government’s foreign policy committee have agreed that after consulting parliament, Finland will apply for Nato membership,” president, Sauli Niinistö, told a press conference. “A protected Finland is being born as part of a stable, strong and responsible Nordic region.”

Nato allies expect Finland and Sweden to be granted membership quickly, a move Putin has warned would have ‘serious military consequences’

• Russia-Ukraine war: latest updates

Finland is expected to announce its intention to join Nato on Thursday with Sweden likely to follow soon after, diplomats and officials have said, as Russia’s invasion of Ukraine reshapes European security and the Atlantic military alliance.

Nato allies expect Finland and Sweden to be granted membership quickly, five diplomats and officials told Reuters, paving the way for increased troop presence in the Nordic region during the one-year ratification period.

Lithuania plays down threat, claiming Russians already have such weapons in Baltic enclave of Kaliningrad

• Russia-Ukraine war: latest updates

Moscow has said it will be forced to strengthen its defences in the Baltic if Finland and Sweden join Nato, including by deploying nuclear weapons, as the war in Ukraine entered its seventh week and the country braced for a major attack in the east.

However, the Lithuanian defence minister, Arvydas Anušauskas, claimed on Thursday that Russia already had nuclear weapons stored in its Baltic enclave of Kaliningrad, which borders Lithuania and Poland. That claim has not been independently verified, but the Federation of American Scientists (FAS) reported in 2018 that nuclear weapon storage bunkers in Kaliningrad had been upgraded.

Public support for western alliance doubled in both countries after Russia invaded Ukraine, find polls

Sweden’s ruling party has begun debating whether the country should join Nato, and neighbouring Finland expects to reach a decision within weeks, as Moscow warned that the Nordic nations’ accession would “not bring stability” to Europe.

Both countries are officially non-aligned militarily, but public support for Nato membership has almost doubled since Russia’s invasion of Ukraine, to about 50% in Sweden and 60% in Finland, multiple opinion polls suggest.