No (and I didnt make the original comment but I agree with it) - sources have suggested that Hitler's plan was to quickly move east and crush the Russians/Soviets, who he didnt anticipate would offer much resistance, so that he could then focus on the western front. By all accounts, this was pivotal to Hitler's plans as he knew he wouldnt be able to face a prolonged fight on two fronts. The fact the Russians put up more of a fight than he expected (due to Stalin's modernisation - which obviously came at a massive cost of human life) basically put a spanner in the works for Hitler, especially when winter hit and the Germans lost huge amounts of troops due to the harsh climates.
Needless to say, the "correct" answer is that multiple parties were all hugely important in WW2.
The Brits - and particularly their interception of the Zimmermann telegram, which is essentially what persuaded the US to join in, as well as the navy and airforce. Lots of countries had big parts to play. Except the French of course.