From an opinion piece by Donald Kirk, writing in Forbes:
The execution of North Korea’s military chief reflects Kim Jong Un’s deep insecurity about his grip over a recalcitrant elite of senior and mid-level officers and cadres.
Exactly what Hyon Yong-Chol, 66-year-old minister of the People’s Armed Forces, i.e., defense minister, did to incur Kim Jong-Un’s wrath is not clear, but the inference was that he had not only shown contempt for the young leader but also may have disagreed with him on crucial points.
North Korea has not announced the execution, but South Korea’s National Intelligence Service (NIS), drawing upon a wide range of contacts, is seen as credible when it reveals such information. The question is why Kim Jong-Un would order Hyon’s extermination considering that Hyon had just returned from an international security conference in Moscow at which he was photographed displaying rows of ribbons on his chest.
The answer, in the view of Choi Jin-Wook, president of the Korea Institute of National Unification, is that Kim is feeling increasingly insecure in an amosphere of discontent in Pyongyang among many who grew to power under his father, Kim Jong-Il. Hyon’s execution, latest in an ongoing purge of top and mid-level cadres, “is a sign of the weakness of the regime,” Choi told me. “If they are strong enough, they have no reason to kill him.”
Kim Jong-un reportedly flies into rages at any sign of disagreement, much less disobedience. He has ordered at least 15 executions in recent months and at least 75 in the past two years. according to the NIS.
Yonhap, the South Korean news agency, quoted an unnamed official who agreed there were “growing doubts about Kim’s leadership among North Korean ranking officials.” As a result, the official was quoted as saying, “Kim has deepened a reign of terror by purging them in negligence of proper procedure.”