Finland was hardly a German ally; they accepted German help in reclaiming the territory they lost in the Winter War, then would go no further. Hitler desperately wanted them to help at Leningrad, and they wouldn’t. Even Stalin took this into account as the war ended; he re-took what they’d seized in the Winter War, but alone among the countries that fought the USSR along its borders, Finland remained a free country (as opposed to an occupied Warsaw Pact puppet). Finland was no more a German ally than Franco’s Spain; once their countries were secure, they were done fighting.
The USSR wouldn’t have needed to fight in the islands, just on the mainland. Whatever reason you give as to why they didn’t, there was nothing to stop them from rolling into Manchuria afterwards - which they did with gusto. In the end, China, North Korea, and all of former French Indochina ended up in communist hands as a result of that move.
Ummm, Finnish forces took part at Leningrad.
https://en.wikipedia.org/wiki/Siege_of_Leningrad#Finnish_participation
Stalin did actually invade Finland. The only reason the Russians stopped was because the Finnish fought the Red Army to a stalemate, negotiated an armistice (the September 1944 Moscow Armistice) and then joined the Allies.
It should be remembered that China was absolutely communist in areas during the war - the Communists and Nationalists were fully engaged in combat in 1927, long before the Japanese invaded.
The USSR didn’t have the resources to spend on mainland Asia until it was clear Germany was prostrated; additionally, it was agreed at the various conferences that the USSR would continue to concentrate in Europe - remember, the policy was Germany first, with Japan as a side show.
You seem to be remembering a lot of things about WW2 that just weren’t so.
Additionally, French Indochina ended up in Communist hands because after the war we let the French take it back as a colony, where they resumed their abuses of the populace, only writ larger. At which point, the Vietnamese, fresh off evicting the Japanese and still armed, strongly objected.
No less a person than Ho Chih Minh went to Washington to ask that the French be removed or at least the aid with which he’d fought the Japanese to be continued. Washington, in their stupid “Hey, let’s appease the French” mindset, told him no. “Uncle Ho” said “screw that” and turned to people that *would* support his people. We all know what happened next.
We should have told the French, “No, you don’t get any of your colonies or territories that we had to liberate or support back” but nooooooooooooooooooooooooooooo.......