Well, again context helps (like you showed in the other parts of your comment). Note my comment does not imply the Soviet Union was right in waging war against Finland:
From Wikipedia's article on the Winter War:
> "Joseph Stalin regarded it a disappointment that the Soviet Union could not halt the Finnish revolution. He thought that the pro-Finland movement in Karelia posed a direct threat to Leningrad and that the area and defences of Finland could be used to invade the Soviet Union or restrict fleet movements. During Stalin's rule, Soviet propaganda painted Finland's leadership as a "vicious and reactionary fascist clique"
Again, Stalin's fear and paranoia about other powers invading its territory, which in turn mandated creating buffer or safe zones around the Soviet Union. It's not outlandish, given the USSR's many actual enemies and their history of interference within Russian.
His fears partially proved true (with some degree of self-fulfilling prophecy) when Finland played a (limited) role in assisting the Germans with Barbarossa and the Siege of Leningrad.