Kim Pops H-Bomb ICBM Ready, page-28

North Korea's nuclear testing and continued belligerence legitimizes the arming of both South Korea and Japan, autonomously, or with the assistance of other nations like the US.

The greater the period of inaction by China, the greater the deadly arsenal that will build up on their doorstep.

It will not be in China's interest to have a massive arms escalation by its nearest neighbours. A nightmare setting for China would be to have a nuclear armed Japan or/and a nuclear armed South Korea, or at a minimum both of these countries much more militarized. A nightmare setting for China will be for the US to have a legitimate reason to escalate its military presence in the region, allowing the US to deploy its military might throughout the South China sea.

The continued maverick stance of North Korea will legitimize any escalation of weaponry by Japan & South Korea & the US.

Ultimately China will have to act decisively on North Korea in order to preserve its continued dominance in the region.