Isn't that broadly what allies means in geopolitics? Not many relationships are considered allies where one or both sides are going against their own interests, at least in theory?
I get what you mean, but in this case, I'd ask under what circumstances Russia would come to the defense of the US. NATO is an alliance of allies in that sense.
Russia supported the US after the 9/11 attack.
There is probably some degree of aliterative appeal in 'ally to adversary'. But they were viewed as at least neutral in the 90s.
Mitt Romney was also mocked for calling Russia the greatest threat in 2012. I was one of those people. I was wrong.