Who would win in a war russia or America?

It would be 50/50 depending on if allies are allowed or not.
If no allies then America would probably just win due to superior technology.
If Russia performed a surprise attack they would win due to having a quite good military and would leave America little time to react by which time they would be destroyed.

If allies were allowed America would win easily due to close ties with the UK as the UK has about the second best military in the world (after America) so that's the best and the second best together making a formidable force and that's not counting the EU who would help the UK, Russia would get China but lets face it all they have is loads of unskilled people and poor technology (they are a backward country in many ways).

To sum up America would come out on top in most situations. If nukes are involved we are all going to die.