Moscow in April branded Finland's membership of the western alliance an "assault on our security" and vowed to "take countermeasures... in tactical and strategic terms".

Finland shares a 1,340-kilometre (830-mile) border with Russia. Its NATO membership has doubled the US-led alliance's border with Russia.

"Russia announced military reforms and the creation of new units in northwest Russia already last December, referring to the expansion of NATO's presence," Finnish Foreign Minister Elina Valtonen told AFP in an email.

"These efforts do not seem to have progressed very quickly," she added.

"Russian resources seem to be tied up elsewhere at the moment," she said, referring to Ukraine.

"The situation on the eastern border is calm."

The Kremlin's offensive in Ukraine upended Europe's security landscape and prompted Finland to drop decades of military non-alignment to join NATO.

The Nordic country of 5.5 million people is also in the process of fencing in a 200-kilometre section of its border with Russia, due to be completed by 2026.

At present, Finland's borders are secured primarily by light wooden fences, mainly designed to stop livestock from wandering to the wrong side.

Russia recently reiterated the threat on August 9 when it accused both Finland and Poland of threatening its security, vowing a response to the multiplication of "threats" to Russia's western frontier.

Poland has strengthened security on its border with Moscow's close ally Belarus.

"Threats to the military security of the Russian Federation have multiplied in the western and northwestern strategic directions," Russian Defence Minister Sergei Shoigu said at a meeting with military officials.

Those risks "require a timely and adequate response," he added.

Valtonen said Finland was "always well prepared for different situations. Including this one".

"NATO is a defensive alliance and does not threaten Russia any more than Finland does... Russia's criticism of NATO is a long-standing position and it is nothing new," she said.