"[The] Finns were not so insane as to imagine that they could achieve a military victory. Instead, as a Finnish friend expressed it to me, “Our aim was instead to make Russia’s victory as slow, as painful and as costly for the Russians as possible.” [One] platoon skied through the forest, invisible in their white camouflage uniforms, to within firing range of a Soviet column. They then climbed nearby trees while carrying their rifles, waited until they could identify the Soviet officers in the light of the bonfire, shot and killed the officers, and then skied off, leaving the Soviets frightened, demoralised and leaderless. Finally, the Finnish army, like the Israeli army today, was effective far out of proportion to its numbers, because of its informality that emphasised soldiers taking initiative and making their own decisions rather than blindly obeying orders. Neighbouring Sweden, although closely connected to Finland through long-shared history and shared culture, refused to send troops out of fear of becoming embroiled in war with the Soviet Union. But why, in March 1940, did Stalin not order the Soviet army to keep advancing and to occupy all of Finland? One reason was that the fierce Finnish resistance had made clear that a further advance would continue to be slow, painful and costly.

When I visited in 1959, knowing almost nothing about the history of Finland’s two wars with the Soviet Union, I asked my hosts why Finland deferred to the Soviet Union in so many ways, imported the inferior Moskvich cars and was so afraid about the possibility of a Soviet attack. I told my hosts the US would surely defend Finland if the Soviet Union attacked. In retrospect, there was nothing more cruel, ignorant and tactless that I could have said to a Finn. Finland had bitter memories that, when it was attacked by the Soviet Union in 1939, it had not been helped by the US, Sweden, Germany, Britain or France. Finland had to learn from its history that its survival and independence depended on itself."

https://www.noted.co.nz/currently/currently-history/jared-diamond-finland-shows-nations-can-survive-thrive