The sovie union and china were never good friends. Soviet Communism != Chinese communism no matter how much the soviet union wanted it to. Now Russia is democratic, and China is a free market communist nation. Never say never but in an actual war we really dont have competition, Europe is a joke, Russia is too poor, and China doesnt have to go to war, everyone in the world gives them money and invests in their economy. And its not like russia is dying to get at us, if any nation was to fire the first shot it WOULD be us thanks to our moron president. Even then i dont see anything in the near future that would bring the entire world into war, all the major players are in the same UN allaince. All the major companies of the world are making money from the global market. Its not like when Japan needed our oil to make their empire, or when germany was getting fucked in the ass because of the Versailes treaty. We arent isolationists anymore, we run this shit. And we are in turn run by countries that bought our bonds and can flood the market with our money to keep us in check. The next frontier space is going to need a global effort, really cant do that if the world was torn apart by war.