2) if the war is being fought in Asia, the U.S. loses. Land wars in Asia are hard to win for anyone, but especially when you're an ocean away from Asia. If the war is being fought in the western hemisphere (i.e. China and Russia are attacking to try to conquer the U.S.), then the U.S. wins. If it's being fought in cyberspace or outer space, then there isn't ever really a resolution, just a lot of nastiness until eventually a truce of some sort happens.
3) the fact that point (2) is well known to all three country's leaders, reinforces point 1. And, thank goodness.
In map 1 paint all the countries that would loose a war if China attack them today.
In map 2 paint all the countries that would loose a war if Russia attack them today.
In map 3 paint all the countries that would loose a war if USA attack them today.