Could Finland cut off the Kola Peninsula?

If Finland joined the war, could Finnish forces reach the White Sea coast and cut the Kola Peninsula off from the rest of the Soviet Union?

It is doubtful without substantial support. Finnish forces were formidable defensively, but this would require a major offensive against a fully mobilised Soviet Union.

The proposed operation would turn Finland's familiar defensive advantages into a very different military task. Finnish forces were strong when fighting on their own ground and terms. Reaching the White Sea coast would demand sustained offensive movement against a fully mobilised Soviet state. Without outside support, Finland would be unlikely to sever the peninsula successfully.