,,, I suspect China and Russia will use North Korea and make the most of the middle east to deplete US resources and then engage when she's on a weaker footing.
Probably what they (China and Russia) will do... Also,they will try to use Iran, North Korea, and islamic terrorists to strike the first blow.
Also, both of those countries could smuggle in Nuclear cruise missles into Cuba, venesuelia, ect without our intel knowing about it.