Great question. Russia and China are natural enemies, but accidental allies due to U.S. foreign policy. They share a continent, which means as aspiring super powers they'll both compete for natural resources in central Asia. The fact of the matter is that Russia and China are already teaming up against the U.S. to remove the USD as the world reserve currency. They're involved in undermining U.S. influence around the world; especially in Europe, Africa, and South America. In economics, business/trade, diplomacy, technology, and espionage, we're already in a cold war, but just short of a hot war. While the Pentagon has moved back to attaining the capability to fight a "two-front war", I don't see the U.S. engaging both countries at once. I think it has to be one or the other, in which case the other not at war with the U.S. should make the best of a good situation. That might mean we choose the Baltics or the South China Sea, but probably not both.