It would seem to me that of all the provocations that the North Koreans do, the nuclear tests are probably the ones that most concern the Chinese considering how close they are occurring to their border. It seems for now they may have been able to convince the Kim regime to delay their fifth nuclear test:
China reportedly speculates that an internal political assessment led to North Korea’s decision not to conduct a nuclear test around the time of its ruling party congress held early this month.
According to a senior South Korean government official stationed in China who spoke to reporters in Beijing on Thursday, China urged North Korea to refrain from carrying out its fifth nuclear test. The source quoted a senior Chinese official but added that it can’t be concluded that Pyongyang stopped short of a test just because of China’s request.
The official said that Beijing believes the North must have politically evaluated that a nuclear test will be a minus to the party congress. [KBS World Radio]
You can read more at the link.