Russia warns Finland of retaliatory military measures if joins NATO

Finland's membership in NATO would represent a threat to Russia, the Kremlin warned Thursday, after Finnish leaders threw their support behind joining the Western military alliance "without delay."

"A renewed expansion of NATO will not make our continent more stable and secure," spokesperson Dmitry Peskov said, adding that Russia would be assessing the consequences of Finland joining the Alliance with a view to its own security.

Finnish President Sauli Niinistö and Prime Minister Sanna Marin had given their official backing to membership hours earlier, moving the Nordic country much closer to making an official request to NATO in coming days.

Finland, which shares a 1,300-kilometre-long border with Russia, has seen public support for membership soar since the Kremlin's war against Ukraine erupted in late February.

"Helsinki should realize the responsibility and the consequences of such a move," the Russian Foreign Ministry said, warning that "Russia will be forced to take retaliatory steps both of military-technical and of other nature."

"History will decide why Finland should turn its territory into the frontier of a military standoff with the Russian Federation while losing its independence in making its own decisions," the statement quoted by Russia's TASS news agency said.

While criticised by Moscow, Western leaders were quick to embrace the endorsement.

NATO Secretary General Jens Stoltenberg said Finland "would be warmly welcomed" into the alliance, adding that he expects the formal accession process to be "smooth and swift."

Polish Prime Minister Mateusz Morawiecki tweeted that his country "supports Finland joining NATO as quickly and smoothly as possible."

Charles Michel: 'Historic step'

European Council President Charles Michel hailed the announcement as "a historic step" and a major boost for European security.

"With Russia waging war in Ukraine it’s a powerful signal of deterrence," he said on Twitter.

In a recent survey, 76% of respondents in Finland were in favour of their so-far neutral country joining the Western military alliance.

"NATO membership would strengthen Finland’s security," the statement from the Finnish president and prime minister said.

"As a member of NATO, Finland would strengthen the entire defence alliance. Finland must apply for NATO membership without delay."

The leaders said that they hoped "the national steps still needed to make this decision will be taken rapidly within the next few days."

Several political parties in neighbouring Sweden have also signalled their backing.

Other Nordic countries Denmark, Norway and Iceland have been members of NATO since its founding in 1949.

Sweden, which like Finland is not a NATO member, is expected to announce its decision on NATO membership in the coming days.