Well, this is not as simple as mr. Radio tries to show it.
First of all, three Pribaltic states signed "military assistance" treaties with USSR. The reason was obvious: nazis openly threatened their independance and integrity. Memel/Klaipeda is a good example.
The problem with Finland was different. USSR wanted to secure Leningrad from an "indirect agression", a term not recognized by Western powers, mostly because they were possibly counting to use indirect agression against USSR. More to say, indirect agression was exactly what happened in 1941 when German troops used Finland as a beachead. It is clear and obvious that if the border remained at Sestroretsk, only 32km from Leningrad (now it's much closer - the city grows), enemy troops could reach Palace square and even industrial districts in the South of Leningrad in a few hours.
Soviet government offered Finland a fair exchange of Karelian Istmuth for two times more land in Karelia, but Finnish government refused. Then - Mainila happened, and the war began. Finland probably relied on Western military assistance, but it didn't come in time. Future "allies" let Hitler rape Poland without waving a finger, so they wanted him to attack USSR and didn't want to engage in future War. It's pretty obvious, and many Western sources share this point of view.
After complete defeat of Finnish defence in March 1940 their parliament was wise enough to sign a cease fire on the conditions offered by USSR before the war. It's interesting that Mannerheim insisted on agreement with Soviet Union before the war... He was a former Russian general and understood that Finnish army doesn't stand a single chance against Russians. Two weeks of defence promised by Mannerheim turned into the worst campain for Russian/Soviet army since maybe 1905. I wonder what could happen if Russians didn't blow up forts of Finnish Gulf in 1918... I spent my childhood in the military harrison, "summer quarters" of the Komarov military engineering college in Privetnenskoe, literally on the ruins of fort Ino. It looked really impressive even 60 years after it was blown up...
I have once wrote here that my Father was a schoolboy in 1940, he lived in Rostov on Don. His school was turned into a hospital in winter 1940, it's hard to imagine the losses if wounded warriors didn't fit into hospitals even that far South... Mostly frozen, less - wounded...
The point where most of the Finns disagree with me is that Stalin didn't want to occupy the whole Finland. After Mannerheim line was broken in March 1940 and Kirponos's tanks croosed the ice of Finnish gulf - everything was over, and nothing could stop Red Army. Instead of occupation Stalin preferred to agree on pre-war conditions.
I have to point out that all USSR foreign policy (as well as internal policy
) in late-30s had one simple purpose: to survive in the inevitable War. The non-agression pact with Hitler didn't fool anyone - the war was in the air, and the enemy was clear.
