I'm with HoreTore. Post WW2 the USSR had the most fearsome army on the planet. Allied tanks were a joke, but had better planes and Navy. The reason the two sides didn't go for each other was that neither side saw a way of winning without losses that were so vast as to make any victory pointless.

The Germans would have taken the Russians with more preparation - especially if the Italians hadn't screwed up in the Balkans. Attack as the Spring progresses. There was basically the one chance - but with their nukes no chance.