>>515612481
>USSR was helping Germany grow and expand.
Yes at first. You seem to fundamentally not understand Stalin's overall geopolitical strategy so I'll summarize it for you. Stalin wanted Germany to first the rest of the west ultiamtely weakening both sides so that Stalin could swoop in and conquer all of Europe.
This strategy failed however after 1940 when France was so easily and quickly defeated. Stalin hoped for the conflict to continue however with possible a German invasion of Britain so delayed a while. When it became clear Hitler had no interest in a further war with Britain Stalin was then in a conundrum.
If he attacked Germany, Germany could no longer weaken Britain for him. If he sided with Britain, Germany would attack the USSR.
By the time of April 1941 and his cadets speech he had decided on war with Germany as Hitler refused to concede to anymore of Stalin's territorial demands in Eastern Europe (Romania Bulgaria, etc) making war inevitable. The only question by that point was when the war would start and who would start it, not "if" there would be a war, that was already determined.