1. From the military: North Korea's missiles and nuclear weapons can threaten to blackmail the United States and Japan, but also threaten to blackmail China; can hit Japan, more able to hit Beijing, in which the decisive role is geographical space. As long as North Korea has nuclear weapons, is a threat to Beijing, China, is a substantial threat, China must be guarded against. 2. economically: when China's development into a bottleneck stage of the critical period is forced to pay a huge cost in the defense of North Korea.

3. From diplomacy: North Korea in the face of national survival or not, in the face of the United States and other external strikes, including nuclear strikes, can be used through the use of nuclear weapons against China, forcing China to the United States and other countries to carry out nuclear counterattacks in order to curb the United States and other countries on North Korea's strikes, so as to realize the nuclear bondage, but also China will be in an extremely passive situation.

4. From the follow-up: North Korea already has nuclear weapons, then Japan and South Korea also have a reason to have nuclear weapons, there is a possibility of triggering a nuclear race in the East Asian region, which makes China around the unstable factors greatly increased.