The stunning execution of Kim Jong-un's powerful uncle strips China of its most important link to North Korea's leadership and deepens concerns over how the unruly neighbor will proceed on Beijing's key issues of nuclear disarmament and economic reform.
Facing heightened uncertainty, Beijing will likely avoid for now any response that might boost panic or paranoia in Pyongyang, where China is both valued and resented as a key backer of Mr. Kim's regime.
"It's like when you have a gas leak. You want to be very, very careful not to set off any sparks," said Jingdong Yuan, an expert on Northeast Asian security at the University of Sydney.
At the same time, China is likely dusting off its contingency plans for instability or even a regime collapse that could see thousands of refugees swarming across its borders, put the North's nuclear facilities at risk, and prompt action by the US and South Korean militaries, Mr. Yuan said.
"This is not a welcome development as far as China is concerned," he said.
Long considered Kim's mentor and the country's No. 2, Jang formed a key conduit between Pyongyang and Beijing because of his association with the government of Kim's father, Kim Jong-il, along with his support for China-backed reforms to revive the North's moribund economy.
Jang met with top Chinese officials during their visits to Pyongyang, and in 2012, Jang traveled to China at the head of one of the largest North Korean delegations ever to visit the Chinese capital to discuss construction of special economic zones that Beijing hopes will ensure North Korea's stability.
His execution on myriad charges from treason to drug abuse further diminishes China's narrow influence on the government of the younger Kim. Despite being North Korea's only significant ally and a crucial source of trade and aid, Beijing has been unsuccessful in persuading North Korea to rejoin six-nation nuclear disarmament talks, while its overwhelming desire for stability along its northeastern border prevents it from getting overly tough on its neighbor.
Jang's China contacts weren't explicitly mentioned in the official litany of crimes against him, although he was accused of underselling North Korean mineral resources for which China is virtually the sole customer. His China ties also were implicitly criticized via a reference to corruption related to a 2011 project in conjunction with China at the Rason special economic zone.
Jang, North Korea's official media said, "made no scruple of committing such act of treachery in May last as selling off the land of the Rason economic and trade zone to a foreign country for a period of five decades under the pretext of paying those debts."
Jang's execution comes at a delicate time in bilateral relations. While Kim's father made a number of visits to China, the new leader has yet to travel outside North Korea and has repeatedly defied Beijing's calls not to launch missiles and stage nuclear tests. That has in turn spurred Beijing to make unusually bold criticisms and sign on to tightened United Nations Security Council sanctions, arousing an angry response from Pyongyang.
The chill in relations was somewhat relieved following the visit by a top North Korean general to Beijing this summer, but diplomats say China remains committed to working closely with the international community on enforcing sanctions and coaxing Pyongyang back to nuclear talks.
Still, Jang's execution isn't expected to bring major, immediate changes in a relationship that has been remarkably consistent over the many decades since China sent troops to save the North Korean regime from extinction in the 1950-53 Korean War.
Wang Junsheng, a North Korea-watcher at the government's Chinese Academy of Social Sciences, said relations might even benefit since the move leaves Kim in a stronger position than ever to guide North Korea's ties to Beijing, the strengthening of which benefits both sides.
"Kim has now finished consolidating his power and doesn't need to take drastic change in his foreign policy. Jang was merely a person who offered advice and implemented policy," Mr. Wang said.
China's response to Jang's dramatic purging has been extremely low key, emphasizing that the issue is North Korea's internal affair and expressing its hopes for stability and economic development. Along with stifling panic, Beijing may be hoping that its nonintervention will spare some of Jang's pro-China associates from being targeted for removal under the North's policy of collective punishment.
As with South Korea, the United States and other interested parties, Beijing is struggling to analyze the current state of affairs in Pyongyang and ascertain Kim's positions on key topics.
While Kim has enunciated a policy of jointly pursuing nuclear weapons and development, it isn't clear whether he views economic reforms as strengthening his rule or undermining it by inviting unwelcome comparisons with foreign economies and by introducing foreign concepts and practices, said Shi Yuanhua, director of the Center for Korean Studies at the Fudan University.
"North Korea couldn't live without China, but cooperation in developing the special economic zones may be affected to some extent," Mr. Shi said.
Overall, Kim's attitude toward economic reform in cooperation with China remains a mixed bag, said Fang Xiuyu, a North Korea expert at Shanghai's Fudan University.
Even as Pyongyang was announcing Jang's purging, North Korean and Chinese representatives were signing contracts on cross-border high-speed rail and highway connections, Ms. Fang pointed out.
"I don't think North Korea's economic relations with China will be affected because of this particular incident, but all we can really do for now is speculate," she said.