Last December, the world was appalled by the North Korean government’s execution of Chang Song Thaek, an uncle-in-law of the young Supreme Leader Kim Jong Un and the regime’s de facto second in command.

Given Chang’s pivotal role in steering North Korea’s moribund economy, his execution raised serious doubts about the regime’s stability — raising fears of the collapse of a dynasty that possesses weapons of mass destruction. Ultimately, Chang’s execution really affected only one other country, North Korea’s only international ally: China.

Five months later, there remains no clear account of the motivation behind the decision to eliminate Chang. Nonetheless, a series of in-depth analyses have offered some insight into the power struggle among North Korea’s leadership over the distribution of resources — including mining and other concessions — that are closely linked with the regime’s foreign policy.

Chang was known to have given priority to the regime’s economic survival over the development of nuclear weapons. China — North Korea’s sole supplier of oil and food — strongly supported this approach. Why would the North Korean regime jeopardize its relationship with China, the only country that could bring it down immediately, just to execute one official?

Assuming that Kim is rational, he must have had good reason to believe that the Chinese lifeline would be sustained, even if he executed China’s favorite North Korean interlocutor.

The only possible explanation lies in the Chinese government’s struggle to control the Shenyang Military District, which borders North Korea. Otherwise, China may well have stopped supplying oil and food to the North after Kim’s regime conducted nuclear tests — in line with U.N. Security Council Resolutions 1718 and 1874. The resolutions imposed stringent economic sanctions against North Korea, and China could have vetoed both of them in order to avoid risking North Korea’s collapse and the inflows of refugees that would result from it. But it chose not to. The problem was that the Shenyang Military District refused to implement them.

Even if China deliberately acted falsely — endorsing sanctions, while knowing that it would not enforce them — it would have used its support for Chang to tame Kim. Chang’s execution was thus a straightforward challenge to Chinese President Xi Jinping — a move that, under normal circumstances, would prompt China to suspend, or at least reduce, its support for North Korea.

The fact that China did not suggests that Kim has somehow secured a lifeline directly from Shenyang.

Bo Xilai, the former Chinese Communist Party (CCP) chief in Chongqing who was sentenced last year to life in prison for bribery, embezzlement and abuse of power, spent two decades in an area within Shenyang, including in stints as mayor of Dalian City and governor of Liaoning Province. Exploiting popular discontent fueled by rapidly rising inequality, Bo, who had been widely viewed as a likely candidate for a top leadership position in the Politburo Standing Committee, adopted a neo-Maoist stance that China’s top leadership could not abide.

But as the economy slows, the regime’s legitimacy is increasingly being questioned, which implies that neo-Maoism may yet make a comeback. Indeed, it is a stance that resonates deeply with the egalitarian tradition of the People Liberation Army (PLA), as well as with its institutional interests, particularly those in the Shenyang District.

As it stands, in order to meet China’s strategic and operational needs in coping with the United States and its allies, particularly Japan, the government is emphasizing the modernization and professionalization of the navy and air force. To this end, it has been redirecting spending away from the army.

Of the seven military districts, Shenyang’s mechanization and mobility make it the most potent. In fact, it houses four of the PLA’s five mechanized army corps, with the fifth protecting China’s strategic nuclear forces in Sichuan. In 1992, China’s government established two additional mechanized corps in Shenyang District to deter or respond to tumult in North Korea.

Given the CCP’s fear of warlordism — which played a key role in China’s dismemberment after the fall of the Qing Dynasty in 1911 — this imbalance in favor of Shenyang is odd.

The lack of a countervailing ground force in northern China makes it vulnerable to a possible coup by Shenyang, which has already taken advantage of its influence on the North Korean regime to put pressure on China’s leaders.

This has led to speculation that Chang’s execution was retaliation, endorsed by Shenyang, for Bo’s arrest and the ongoing purge of his supporters including, most recently, the powerful former chief of internal security. In other words, what appeared to be a form of political-military brinkmanship by Kim may actually be a manifestation of Shenyang’s reaction to Xi’s struggle to reassert party authority over Bo’s faction and its supporters in the military.

Thus, China’s ability to bring North Korea into line — a capacity that the U.S., in particular, believes Xi has — may in fact depend on the outcome of a more epochal struggle to bring the PLA fully under central authority.

Twenty-five years after the military rescued the party by crushing pro-democracy protesters in Tiananmen Square, Xi’s potential strategy for doing so — a purge of high-level military figures — may incite a major internal fight.

Masahiro Matsumura is a professor of International Politics at St. Andrew’s University (Momoyama Gakuin Daigaku) in Osaka. © 2014 Project Syndicate

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