He is trying to entice the US or ROK to fire first. China's policy is that they will only respond to defend the DPRK if they are not the aggressor so if they fire the first shot then supposedly China will not respond.
It's fast coming a time that they will be a threat to China as well. I think it's far more likely the Chinese will invade somewhere down the line. -- Fight Cancer! Join DSLR's Team Discovery