USSR was not imperialist. It never exerted economic violence or exploitation on other countries (was an exporter of resources and importer of manufactured goods), and materially fought fascism in Europe earlier than anyone else such as 1936 support of Antifascists in Spanish Civil War.
In the Russian Civil War, the Russian Bolsheviks seized control of the former empire’s territories and founded the Soviet Union (USSR). Although claiming to be anti-imperialist, it had many similarities with empires. It was involved in many foreign military interventions and in regime change throughout the world, as well as Sovietization. Under Joseph Stalin, the USSR pursued internal colonialism in Central Asia[2] by massive forced resettlement. Under the Molotov–Ribbentrop Pact, the Soviet Union and Nazi Germany divided eastern Europe between themselves. At the end of World War II, most eastern and central European countries were occupied by the USSR; these Eastern Bloc countries were widely regarded as Soviet satellite states.
So yes, this is essentially three imperial states joining forces to fight a fourth imperial state (Nazi Germany) which was perceived as an existential threat to them.
USSR was not imperialist. It never exerted economic violence or exploitation on other countries (was an exporter of resources and importer of manufactured goods), and materially fought fascism in Europe earlier than anyone else such as 1936 support of Antifascists in Spanish Civil War.
https://en.wikipedia.org/wiki/Russian_imperialism
So yes, this is essentially three imperial states joining forces to fight a fourth imperial state (Nazi Germany) which was perceived as an existential threat to them.