Signs Of A Rift Along The Beijing-Pyongyang Axis?

In Panmunjon, in the heart of the demilitarized zone, the border between the two Koreas can be found drawn across a table. A white stripe painted on the wooden surface separates the sides where the belligerent factions sat in 1953. After three years of shocking violence, the war was finally ended by a difficult armistice. Peace is still a long way away, and the line across the table is still ominously present.
Now even that bizarre boundary is at risk of being compromised. North Korea has declared the armistice invalid, blocked all of the already limited cross-border travel, and cut off the red-phone hotline with the South, the last line of defense to prevent a military crisis. The moves have been accompanied by nationalistic rhetoric against the “treacherous puppets” in South Korea.
The threats have extended to the United States and by default to the pax Americana that has ruled over the Pacific since the end of WWII. Pyongyang has effectively fanned the flames after the passage of the most recent United Nations resolution. Angered by North Korea’s insistence on continuing its nuclear weapons program, the assembly in New York City did not hesitate to act after Pyongyang’s latest nuclear test last month. The political condemnation is coupled with a tightening of economic sanctions: financial transactions have been limited, suspicious commerce will be inspected, landing rights have been revoked, and further restrictions on travel and commerce.
North Korea’s fiery reaction is not, however, just a result of the sanctions. This time around, the sanctions were co-sponsored by China. Drafted by the US and Chinese ambassadors, the motion to condemn South Korea was easily passed by unanimous decision in the Security Council, and so for the first time China has conclusively kept its distance from Pyongyang. Its calls to reconsider the nuclear tests, to tone down the rhetoric, and to avoid useless conflict were ignored. China had hoped that Kim Jong-Un would be less combative, that his dependence on the military would turn out to be less than his predecessor’s. In the beginning of his reign there were in fact some signs of a possible opening. The North Korean economy seems far away from the crisis, private initiative is still in its infancy but at least it is not being repressed, and even the traditional restrictions on daily life, especially in the capital, seem to be loosening, but the regime is unable to deviate from its need to escalate conflict to maintain its grip on power.
On the other hand, Beijing needs stability. It needs to maintain its friendly relationship with Seoul, and avoid exacerbating its row with Tokyo; cooperation with the two other Asian capitals is economically essential. If the situation in North Korea were to unravel, Beijing would have to manage a dramatic situation: millions of refugees and a potential reunification, to its distinct disadvantage. This time, the idea of South Korean troops and their American allies at their southern border is a distinct possibility, and this is the reason for Beijing’s traditionally cautious approach. There is no more ideological affinity, nor the defense of a strategic ally in the Cold War, just the alarming impossibility of controlling an (ex?) ally, proud and unpredictable.
The effects of the new sanctions will likely soon be absorbed in the endless skirmish that has enflamed the Korea peninsula for the past 60 years. What remains to be seen is if these first signs of a rift between Pyongyang and Beijing will spread, and most importantly if China will be able to manage a complex situation that is has begrudgingly inherited.