China should be worried if the mountain where North Korea has had 6 bomb tests implodes (collapses). That would release radiation and would affect Russia (first) and then China.
The Winter Olympics are only a few months away just miles from the DMZ. South Korea is hosting these Olympics...
Hence the actions by Kim. The Olympics will be spitting distance from North Korea, and Kim will have 24/7 worldwide coverage on anything he says or does.
Going to be ugly if that SOB isn't taken out by the end of this year.