Historical USSR Expansion PoDs?

[True Whig]

Does anyone know about (or even have a list of) potential, historical PoDs when the borders of the Soviet Union proper (like Union Republics, not puppets) could have been expanded? Whether this means fully integrating puppets or annexing new territory (e.g., Manchuria?), it doesn't matter. It's a topic I'm genuinely curious about but just am not really sure where to start looking.

 

[Cudymcar]

Gao Gang, CCP head of Manchuria, during his meeting with Stalin in July 1949, proposed making Manchuria a Soviet republic. Stalin's answer was "no".

 

[seraphim74]

Todor Zhivkov, communist leader of Bulgaria, offered to make his country a full member of the USSR, although there are doubts about sincerity of his proposals ( he made them twice in 1963 and 1973). The Soviet were not interested.
I think that post WW2 the Soviets were not particularly eager to aquire new republics. New territories yes, but whole nations? No, too much problems. They prefered to have satelite states.

 

[Kuggy]

Gao Gang, CCP head of Manchuria, during his meeting with Stalin in July 1949, proposed making Manchuria a Soviet republic. Stalin's answer was "no".

IIRC, Mongolia tried to do the same thing a couple times, Stalin's answer was also "No" lmao, mostly because I don't think he wanted such a long border with China, nor did he want to annoy the Chinese

 

[Beatriz]

Gao Gang, CCP head of Manchuria, during his meeting with Stalin in July 1949, proposed making Manchuria a Soviet republic. Stalin's answer was "no".

During the Japanese occupation, the population of Manchuria was recorded as 50 million, and the Soviet population in 1939 was 168 millions - which would have increased the Soviet population by a third and making the Han Chinese the largest minority ahead of Ukranians