Meh, North Korea. They are just a crazy poverty stricken country With a couple of cobbled together nukes they only MIGHT be insane enough to use and if they do they would likely get wiped off the map.
China on the other hand... China basically has us(U.S.) by the balls economically... if country's economies had balls...
Unless I'm mistaken. My opinion admittedly is pieced together from bits from internet news.