Vladimir Putin threatens ‘response’ if Nato military infrastructure deployed in Sweden and Finland

Deployment of Nato military infrastructure in Finland and Sweden will trigger a response from Moscow, Vladimir Putin warned as the two Nordic nations took steps to join the alliance after the Russian invasion of Ukraine.

The expansion of Nato to include Sweden and Finland poses “no direct threat for us ... but the expansion of military infrastructure to these territories will certainly provoke our response”, Putin said during a televised summit meeting of the Collective Security Treaty Organisation, a Moscow-led military alliance.

Sergei Ryabkov, Russia’s deputy foreign minister, said: “This is another grave mistake with far-reaching consequences.

“The general level of military tensions will increase. They should have no illusions that we will just put up with this. It is a pity that common sense is being sacrificed for some phantom ideas about what should be done in the current situation.”

On Monday, Sweden officially announced that it will apply for Nato membership as a deterrent against Russian aggression, entering a "new era" after two centuries of military non-alignment.

"The government has decided to inform Nato that Sweden wants to become a member of the alliance," Magdalena Andersson, the prime minister, told reporters a day after neighbouring Finland had made a similar announcement. "We are leaving one era and beginning another." Sweden's Nato ambassador would "shortly" inform the alliance, she said.

On Monday, France said it fully supported the Swedish application. Denmark and Norway said they wanted both nations in the alliance and would help them if they were attacked.

Public support for joining Nato in the two non-aligned countries soared after Russia invaded Ukraine, which, like the Nordic nations, is not a member of the alliance.

The move is a dramatic turnaround from the two countries’ military non-alignment policies, dating back more than 75 years for Finland and two centuries for Sweden, with both expected to join Nato at the same time.

It came after Ms Andersson had gone to parliament on Monday to secure backing for the move. Her governing Social Democrats dropped long-standing opposition to joining Nato on Sunday, but she said she did not see any direct military threat to Sweden at the moment.

Finland, which shares an 830-mile border with Russia, confirmed that it would apply to join on Sunday, while in Helsinki, the parliament began a marathon session on Monday that could last several days.

“Our security environment has fundamentally changed,” Sanna Marin, the Finnish prime minister, told the parliament. “The only country that threatens European security, and is now openly waging a war of aggression, is Russia.” An overwhelming majority of Finland’s 200 MPs – at least 85 per cent – back the decision to join Nato.

The Nordic nations’ applications were expected to be largely a formality because both boast modern, well-equipped armies.

However, Turkey has said it could block Sweden’s application because it wanted the Nordic countries to halt support for Kurdish militant groups present on its territory and lift bans on sales of some weapons to Ankara.

Sweden will send diplomats to Turkey to try to overcome Ankara’s objections, said Peter Hultqvist, Sweden’s defence minister, with a formal decision to hand in an application expected on Monday.

Both countries were reported to have rejected Turkish requests for the repatriation of 33 people with alleged links to Kurdish militants. Nato and the US said they were confident Turkey would not hold up Finland and Sweden’s membership.

Any decision on Nato enlargement requires approval by all 30 members of the alliance and their parliaments. However, diplomats said Recep Tayyip Erdogan, the Turkish president, would be under pressure to yield because Finland and Sweden would greatly strengthen Nato in the Baltic Sea.

According to recent polls, the number of Finns who want to join the alliance has risen to more than three-quarters – almost triple the level seen before the war in Ukraine began on Feb 24. Swedish public support for Nato membership has also risen dramatically, to about 50 per cent.