Russia shares land borders with five Nato allies but the accession of Finland would more than double its direct frontier with the military alliance, reports ITV News Political Correspondent Carl Dinnen in Moscow
Russia has warned that if Finland and Sweden join Nato, the decision would instantly turn them from neutral into hostile countries and potential targets for Russia.
Dmitry Polansky, First Deputy Representative of Russia to the UN, said in an interview with the British conservative magazine UnHerd, that Helsinki and Stockholm know that “the moment they become members of Nato it will imply certain mirror moves on the Russian side".
He continued: “If there are Nato detachments in those territories, these territories would become a target - or possible target - for a strike,” Mr Polansky added.
“Nato is a very unfriendly bloc to us — it is an enemy and Nato itself admitted that Russia is the enemy. It means that Finland and Sweden all of a sudden, instead of neutral countries, become part of the enemy and they bear all the risks.”
Mr Polansky also downplayed the impact of the possible Nato enlargement on Europe’s security landscape, saying that Russia “is ready to face Nato threats and has made the necessary precautions for this".
It comes after Finland's president and prime minister said on Thursday that they are in favour of seeking Nato membership, in a major move, as a result of Russia's invasion of Ukraine.The announcement by President Sauli Niinisto and Prime Minister Sanna Marin means Finland is virtually certain to seek Nato membership - with an application expected in the next few days - though a few steps remain before the application process can begin.
Finland shares a 830-mile (1,340-kilometre) border with Russia, meaning Russia is set to share a land border with another Nato member.
And the coming days could see the military alliance expand even further, as neighbouring Sweden is expected to decide on joining Nato.
"Nato membership would strengthen Finland’s security," the Finnish leaders said in a joint statement, adding: "Finland would strengthen the entire defence alliance," in turn.
"Finland must apply for Nato membership without delay. We hope that the national steps still needed to make this decision will be taken rapidly within the next few days," the statement added.
The Russian ministry said in a statement that while it is up to Finland to decide on ways to ensure its security, “Helsinki must be aware of its responsibility and the consequences of such a move.
“History will determine why Finland needed to turn its territory into a bulwark of military face-off with Russia while losing independence in making its own decisions,” it added.
The ministry’s statement follows Kremlin spokesperson Dmitry Peskov’s comment earlier on Thursday that Finland’s decision wouldn’t help stability and security in Europe.
Mr Peskov said Russia’ response will depend on Nato's moves to expand its infrastructure closer to the Russian borders.
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Why does it matter that Finland intends to join Nato?
The Kremlin has warned of “military and political repercussions” if Finland and Sweden decide to join the alliance, having previously argued that Nato support for Ukraine constituted a growing threat on its borders.
Currently, five countries that border Russia are Nato members, but only six percent of its land borders touch Nato countries.
Should Finland and Sweden apply for Nato membership, there will be an interim period lasting from when an application has been handed in until all 30 Nato members’ parliaments have ratified it.
Since Russia invaded Ukraine on February 24, the two countries have been pondering whether to abandon their decades-old neutrality and join the defence alliance.
The statement from Finland comes a day after Boris Johnson pledged on Wednesday to give Finland and Sweden whatever kind of assistance they request if they come under attack, including military support.
The prime minister signed a historic security assurance agreement with the two nations, pledging to "bolster military ties" in the face of the war in Ukraine.
What happens if Finland becomes a member of Nato?
Should Finland become a Nato member, it would mean the biggest change in the Nordic country’s defence and security policy since World War II when it fought two lost wars against the Soviet Union.
Finland stayed away from Nato during the Cold War to avoid provoking its neighbour, instead opting to remain a neutral buffer between East and West.
Nato Secretary-General Jens Stoltenberg has said the military alliance would welcome Finland and Sweden - both of which have strong, modern militaries - with open arms, and expects the accession process to be speedy and smooth.