Allan: by May 1945, Soviet army outnumbered Allies in Europe almost 2:1. Most Soviets were experienced fighters who pushed the Nazis from Volga to Oder. Most Americans had little to no experience, they didn’t even land in Europe till mid-1944 when Nazi Germany was already crumbling, and German Western Front was by far the least defended of two.

Soviets probably decided not to engage in the war with Allies because they knew that Americans were progressing well in their development of an atomic bomb. If they were to start fighting, Soviet soldiers would be washing their boots in the English Channel before Americans had a chance to perform a first nuclear test.

Re: Battle of Berlin: Russians lost one soldier for every 5 dead Germans, I think it’s pretty good for an offensive.