Nato and America, considering the fact that the Chinese people would probably take their chance and rebel against the government the second the military goes out to fight outside China. China would be stuck fighting two wars, one against NATO and USA and one against its own people. That would leave NATO and USA vs. Russia and North Korea. In addition, Russia isn't as powerful as it used to be and with China out of the equation, I would say NATO and USA.
~Ven0m