There is a view that although (especially in the first stage) their fighting performance is terrible, the Soviet Union is, after all, the winner of the war and has achieved its strategic goals.So the Western Allies have decided to go all out to help little Finland vis-a-vis both the USSR and Germany? And this has led to the Soviets abandoning their hard-fought Winter War gains pretty much entirely?
It is very noble for the British, the French, the Norwegians and the Soviets to be this nice to Finland, but I am quite sceptical about the feasibility and realism of it all.
But the Soviet Union's strategic goal was not to acquire that territory but to provide security (at least from the northwest) to Leningrad. This was not only not realized after the Soviet-Finnish War, but it can be said to have worsened.
Before the Soviet-Finnish war, Leningrad was close to the Soviet-Finnish border and within the range of the artillery. That's right, but who will threaten Leningrad from the northwest?
Moreover, before 1939 Finland did not intend to enter the World War. Of course, perhaps Finland will actively or passively change his position in the 1940s, but did the results of the Soviet-Finnish war eliminate the threats caused by this change?
The Soviet Union gained territory and pushed the border towards Finland a lot. However, no restrictions were imposed on Finnish armaments and Finland’s foreign relations. Therefore, Finland and Germany formed an alliance, and the German army moved into northern Finland.
During the Soviet-German War, the Finnish army easily advanced to the original border and re-incorporated Leningrad into the artillery range. Stalin's depth did not play any role in preventing the Finnish army. Historically, Leningrad did not suffer much from artillery shells from the northwest, not because of the new border that Stalin obtained through the war, but because of self-restraint in Finland.
In fact, the Soviet-Finnish War is an extremely stupid war-not only on the battlefield, but more importantly outside the war.
If there is no Soviet-Finnish war in the northwest direction of the Soviet Union, there may be three cases:
1. A Finland that has always maintained neutrality. In this case, Leningrad will not be blocked for three years. The Soviet Union can put dozens of divisions on one and a half front from the Soviet-Finnish border during the Soviet-German war.
2. A Finland like Norway and Denmark, whose neutrality was destroyed by Germany, even if it does not consider whether the hundreds of thousands of Finnish troops in the war against the Nazis will let the German army fall into the mire, even if Finland is quickly conquered by the Nazis like Denmark and Norway, amidst the chaos, the depth that the Soviet Union could gain in this direction was much greater than the active war against Finland.
3. A Finnish initiative to surrender to the Nazis, of course Leningrad will be threatened because of this, but this is still just what happened after the Soviet Union obtained that new border in history.
The Soviet-Finnish war ruled out the first two situations that were extremely beneficial to the Soviet Union, ensuring that Leningrad had only one of the worst situations in the strategy-and that Leningrad's tactical security through the war... was the same as before the war.