North Korea’s recent nuclear test has once again placed China in the spotlight, with the international community, especially the US, calling upon the PRC to exert pressure on its neighbour to halt its nuclear programme.
What is the nature of the problem being faced by China vis-a-vis North Korea’s pariah stance? What are the constraints impacting the former’s behaviour and how is it likely to respond?

The Nature of the Problem 
China is faced with a unique problem as far as North Korea is concerned. On the one hand, it cannot afford to have a largely disruptive and unstable state at its borders, for obvious reasons; on the other, it has vested interests in preserving a close ally dependent upon itself for its survival. In addition, China cannot push North Korea too hard on the nuclear issue for fears that it might spur the latter into acting rashly. This being said, China also cannot allow North Korea to carry on with its provocative actions. Beijing thus has to maintain a balance between being firm with and, simultaneously, friendly to Pyongyang.   

Contending with the 'Devil'
There are three main reasons why China is feeling the heat from North Korea’s adventurist stance: dangers of proliferation and radiation at its borders, increased military attention from the United States in the region and calls for ‘responsible stakeholding’ by the international system. Fears of radiation are widespread in the north-eastern parts of China, as evidenced by local opinion. According to New York Times journalist Jane Perlez, there has been an appreciable drop in the percentage of Chinese people, who are sympathetic towards North Korea. Moreover, as a designated ‘state sponsor of terrorism’, there are fears that North Korea might share nuclear technology with other states such as Iran, Syria, Pakistan and Yemen. A more dangerous North Korea would lead to greater US attention and involvement in the region, which might interfere with China’s ambitions in Taiwan and the South China Sea. Further, North Korea’s continued provocation of South Korea might provide an opportunity (however remote) for the US to declare war against the former; thus keeping China on its toes.

More importantly, China is keen to project a positive image of its ‘rise’ and wants to be seen as a ‘responsible stakeholder’. With a greater North Korean threat, therefore, China is seething under international pressure and wants to avoid being cornered on the issue. China’s alleged lack of initiative in the Six Party Talks and Beijing’s inherent habit of blaming the US and South Korea for North Korea’s actions has earned China flak from the international community. China is thus keen to be seen as proactively handling the North Korean problem, imposing sanctions and rhetorically chastising the DPRK.        

Countering the 'Pivot'
The most important reason for China’s unwillingness to take meaningful action on North Korea is its desire to maintain Kim Jong-un’s regime. There are three primary reasons for China’s insistence upon regime preservation in the DPRK. Firstly, the prospect of thousands, probably millions of refugees infiltrating China’s porous northeast is one that raises a huge concern for preserving stability within the country. Second, regime collapse in DPRK could trigger a possible reunification under democratic South Korea, which would be friendly to the United States and Japan, leaving China isolated in hostile surroundings. North Korea’s friendship translates into a strategic buffer between China and South Korea (effectively, the 29000 US troops and marines stationed in the latter). As scholars such as Jayshree Bajoria and Beina Xu have argued, China is ferocious about anything that would jeopardise its agenda on Taiwan. With Obama’s slated policy of the “Pivot to Asia” coming into effect, it is hardly surprising that China is even more particular about preserving its North Korean ally. One might argue that the US ‘pivot’ presents the single most important obstacle to Chinese cooperation on North Korea.

Furthermore, China has vested economic interests in North Korea, with many Chinese private businesses, taking advantage of the international ban on trade in luxury items with North Korea, involved in running illicit activities across the borders. Also, North Korea supplies much needed cheap coal and other minerals to energy-hungry China and a ‘no-strings attached’ policy for economic aid seems to be working well for both China and North Korea.

Conclusion: China's Likely Response
China is not going to be an active player in helping to denuclearise North Korea. It is likely to respond with token sanctions and rhetoric and would not act in any substantial way to solve the problem. Chinese policy would be to oscillate between trying to appease both the American and the North Korean camps by appearing to be supportive to both causes.

China’s reluctance to take effective measures on North Korea is driven by its own core political and economic interests. Although it is concerned about issues of proliferation, radiation and state-sponsored terrorism, for now, the advantages (and necessity) of maintaining Kim Jong-un’s regime far outweigh other considerations. Unless the afore-mentioned factors threaten to destabilise the PRC or harm it in any fundamental way, one cannot see why China would want to disturb the status-quo. Needless to say, without Chinese cooperation, the North Korean problem can never be solved; one might have to accept DPRK’s nuclear reality and seek ways to keep North Korea calm.