>>515609316
Stalin would have attacked from the East if he had, where Stalin had a significant advantage in men, tanks, aircraft, etc.

https://en.wikipedia.org/wiki/Stalin%27s_Missed_Chance

look at the table in pic related for ratios of arms and armor.
>>515609468
Defense would mean playing for time and time was entirely on the side of the allies. A quick decisive victory was Germany's only hope, but they failed because of the Soviet military advantage.