I'm a poly Sci major
China likes to push buttons. But like RR said we are too inter connected with our economies to go to war for no apparant reason. The only for see able "problem" would be China taking back Tawain. In that case the US would step in and well God only knows what would happen. We already showed our power by parading two destroyer/ aircraft fleets with many supporting ships around Tawain when China was playing their war games.
N Korea is a little different because in affect they have nothing to lose. They economy sucks and the little fucker is crazy. Of course the only place they would invade is S Korea... Again that war should be fought more like WWII, small amount of media.
Iran is the biggest instigator... pushing buttons to see how far they can push. They have support from all the extremist and automatically ally with any US hating country. IE N Korea.
Im tired. I argue much better verbally, typing is boring