Russia will have to bolster its defences on the border if Finland joins NATO, its ambassador to the EU has warned.
Speaking to Sky News’ Beth Rigby, Vladimir Chizhov said it would “necessitate certain military technical measures, like improving or raising the degree of defence preparations along the Finnish border”.
Finland’s leaders earlier said it must apply to join the military alliance “without delay” to “strengthen” its security.
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The country shares a vast border of more than 800 miles (1287km) with its much larger neighbour – which invaded it at the start of the Second World War.
Mr Chizhov’s warning echoes the Kremlin’s earlier comments that Finland joining NATO would “definitely” be a threat to Russia and would trigger “retaliatory steps”.
The ambassador said he was “deeply disappointed and saddened” by Finland and Sweden’s NATO ambitions.
He said Finland’s membership would “certainly necessitate rethinking of Russian defence posture” but wouldn’t “necessarily [involve] troops and tanks, but certain preparations definitely… like radars, perhaps”.
Russia has long sought to prevent NATO from expanding near its borders and wants Ukraine to become neutral.
Finland’s president and prime minister made a joint statement on its membership ambitions earlier on Thursday, signalling an end to its own policy of neutrality.
They said they hoped a decision on applying would be “taken rapidly within the next few days”.
“NATO membership would strengthen Finland’s security. As a member of NATO, Finland would strengthen the entire defence alliance,” the statement added
“Finland must apply for NATO membership without delay.”
NATO chief Jens Stoltenberg said Finland would be welcomed and that the accession would be “smooth and swift”.
Neighbouring Sweden is expected to decide on joining NATO in the coming days.
Russia’s EU ambassador also insisted the war in Ukraine – or its “special military operation” as it calls it – “was proceeding according to schedule” but was “not as quick as some people would have wanted”.
Efforts to capture Kyiv failed and the country is now focused on taking the eastern Donbas region.
However, analysts – including from the Pentagon – say it’s still making slow progress with things almost at a stalemate, while Ukraine has claimed to have won back some territory.
“Had Russian army followed the pattern of US and other Western countries, we would have steamrolled Ukraine several times by now,” Mr Chizhov told Sky News.
He claimed Russia never intended to capture Ukrainian territory but that it only wanted to provide “security” for self-proclaimed breakaway republics and demilitarise the country.
The ambassador told Sky News he was “sure” there would be a negotiated solution to the war.
“When that will happen I will not try to speculate,” he said.
“When that final solution will look like – in detail – nobody knows. But in principle it will mean that Ukraine will be a neutral state, non-aligned, without foreign military presence in its territory.
“Ukraine will have recognised the Donbas republics, and of course the reunification of Crimea with Russian Federation.”
Ukraine’s President Zelenskyy has said he is willing to discuss neutrality but would not accept a deal that gives up territory or which allows Russian troops to remain in his country.