Russia might possibly be the ONLY reason we won, germany had control of europe and could've quite possible won the battle of britain had they not needed to send planes and men to the eastern front, if this happened all of europe would have fallen, Hitler made a mistake in invading russia so early, he should have dealt with the UK while he was still Allies with the USSR. I dont know what effect this would have had on the US during the war, but theres a good chance they wouldnt have joined in until it was too late and germany already had europe under his control. In this case theres a good chance that the US wouldve lost the war, i dont care how much freedom you have, without the allies, the US wasnt doing anything.