China has been a friend of North Korea for long now. The Chinese have stood by North Korea as their diplomatic ally for a long time, and this fact is quite well known. In fact, it is even suspected that it is China that may have been responsible for North Korea going nuclear.
For a significant period of time now, China has enjoyed good, close relations with North Korea. But now, the times have changed and so are the circumstances. North Korea’s hostile & aggressive activities have brought the region on the brink of a war with the U.S & its allies.
North Korea’s frequent missile tests have been angering the U.S & its allies. North Korea’s neighbors, Japan & South Korea particularly share a greater threat perception than any other country. To add to that, North Korea recently announced with its long range missile tests that it can even hit any target in the U.S mainland. Besides, it had also threatened the U.S of striking its territory of Guam in the event of any aggression.
The above tensions notwithstanding, North Korea even went ahead and tested a Hydrogen bomb. This has added to its tensions with its neighbors and the U.S. So much so that China now fears a full blown theatre of war in dangerously close proximity to its own frontiers.
China believes that excess of North Korean aggression may trigger a full blown war with the U.S, which it naturally believes, is very bad for the region. Any confrontation between a rogue North Korea and an aggressive U.S committed to the security of its allies is likely to leave a lasting damage on the region.
China believes that a full fledged American military involvement due to North Korea’s excessively aggressive activities is not good for its own security.