MOSCOW | Russian President Vladimir Putin said on Monday that Finland's and Sweden's NATO memberships were not "a threat" in themselves, but that Russia would respond to military deployments.

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Such "NATO enlargement does not constitute an immediate threat (...) but the deployment of military infrastructure on the territories of these countries will of course lead to a response", he said at a summit of a regional military alliance in the Kremlin.

"Serious mistake"

The candidatures of Sweden and Finland to NATO in reaction to the Russian offensive against Ukraine constitute a "serious error", judged on Monday Russian Deputy Foreign Minister Sergei Ryabkov.

"This is a serious additional error, the consequences of which will be far-reaching," he said, quoted by the Russian agency Interfax.

According to him, Russia's response “will depend on the practical consequences of the accession” of the two Scandinavian countries to the Atlantic Alliance.

“For us, it is clear that the security of Sweden and Finland will not be strengthened by this decision,” he insisted, noting that “the level of military tension (was going) to increase”.

Sweden's ruling Social Democratic Party gave the green light on Sunday to a NATO bid shortly after Finland's executive announced its desire to join the Western organization that Moscow sees as an existential threat .

For Helsinki and Stockholm, two countries that had never joined the Alliance even at the height of the Cold War, this reversal is the result of the Russian offensive against Ukraine, with Moscow being perceived as a threat by its neighbors.

Finland in particular shares some 1300 km of borders with Russia.

Moscow had, among other reasons, justified its assault on Ukraine by its rapprochement with NATO and the latter's political, diplomatic and military support in Kyiv. The Russian authorities thus wanted to push Westerners away from its borders.

The countries of the Alliance are also supplying a quantity of arms to the Ukrainian forces which have been fighting the Russian army for nearly three months.