Why is Europe our ally? Why is Russia our enemy? Can the entire world be divvied up between allies/enemies of America? Perhaps so, but does it need to be that w

Why is Europe our ally? Why is Russia our enemy? Can the entire world be divvied up between allies/enemies of America? Perhaps so, but does it need to be that way? Can countries just be, other countries? This is what I don't understand, ever since the Soviet Union fell, there hasn't really been a big bad. Capitalism won. America won. How did Russia end up being our enemies again, and will they be our enemies forever? Europe isn't our enemy today, could they be America's "enemy" tomorrow? I don't think the world is as simplistic as "friends" and "enemies".