Didn't anybody catch the Wikileaks story about China's attitude towards North Korea? They see them as a psychotic, unpredictable mooch that would flood them with refuges should war break out or the dictatorship and military somehow implode. They don't want North Koreans except for cheap organs for sale on the black market or death factory labor. The leaks also revealed China's government would enjoy a reunited Korean peninsula as long as U.S. troops stay below the 38th parallel. China's more militant capitalist than communist now, they'd see New Korea as another market place to flood with their toxic, cheap goods. I think we're witnessing the next Cuban Missile Crisis, hopefully cooler heads will prevail, and a non-nuclear conclusion will be reached.
Pretty much this. No one needs to worry about North Korea, they know they are screwed if they do anything.
Iran is a bigger worry, as they are trying to build a bomb, and unlike North Korea, are actually a threat to someone other than Pacific ocean dolphins.