Often the People’s Republic of China takes a lenient stance towards its ally the Democratic People’s Republic of Korea, which is why it was surprising that China signed a UNSC resolution condemning North Korea’s missile tests and authorizing the imposition of further sanctions on the regime in Pyongyang.
China’s willingness to rein in its ally could be indicative of the PRC’s ability to take a lead role in foreign affairs in East Asia. Additionally, given the Senkaku/Diaoyu Islands dispute with Japan, it would help the PRC to be considered a peacemaker in the region.
China’s willingness to have its leader Xi Jinping meet with newly-elected Japanese Prime Minister Shinzo Abe to discuss the Senkaku/Diaoyu Islands dispute offers a glimpse into the foreign policy strategy of the new Premier of the PRC. While it is unlikely, due to past statements he has made regarding the matter, that Xi Jinping will surrender the Senkaku/Diaoyu issue, the DPRK is an opportunity for China to exercise its authority without endangering any core national interests.
Increasingly it seems that the Red Dynasty in Pyongyang has staked its entire legitimacy on its nuclear program, so giving it up might be quite difficult for Kim Jong-un to do, a fact China might readily acknowledge.
The greater fear for the PRC, however, is the collapse of the Kim regime and an ensuing humanitarian crisis as people flood over its borders or the United States intervenes with South Korea. This would position US troops hundreds of miles from China’s capital Beijing, a situation that the PRC would not enjoy.