The North Korean People’s Army, which enjoyed the biggest trust and perks under Kim Jong-il’s “songun,” or “military-first,” policy, bore the brunt of his son’s often bloodthirsty quest to consolidate his authority, analysts said.

The relationship between Mr. Kim and his generals has been epitomized by reams of photographs coming out of North Korea that showed Mr. Kim swaggering while generals twice his age meekly pretended to write down everything he said in their notebooks. General Hyon’s fate was sealed after he was seen dozing off during a military meeting in mid-April, South Korean intelligence officials said.

Kim Dong-yup, an analyst at the University of North Korean Studies in Seoul, saw method in Mr. Kim’s apparent madness: the North Korean leader, who considered his government’s survival dependent on whether he could revive his country’s moribund economy, has campaigned to wrest the vast trade and other economic rights the military accumulated under his father and restore them to the cabinet.

He also tried to help the ruling Workers’ Party reclaim control of the military by making a civilian party technocrat, Hwang Pyong-so, a vice marshal and installing him at the top of the military hierarchy.

“Kim Jong-un may have felt a need to suppress discontent and skepticism rising within the military elites about his rule by making an example out of their minister, General Hyon,” said Mr. Kim, the analyst. “This may be the beginning of a new round of disciplining the military.”

Cho Han-beom, a senior analyst at the government-financing Korea Institute for National Unification in Seoul, said that Mr. Kim was taming the generals with the help of the Ministry of State Security, the North’s secret police, and the Workers’ Party’s Department of Organization and Guidance, which was widely believed to have engineered the purge of his uncle, Mr. Jang, once the North’s second-most powerful official. The top ranks of the two agencies have so far survived Mr. Kim’s rule with few casualties.

“Unlike Kim Jong-il, Kim Jong-un is only wielding sticks without a firm grip on the military,” Mr. Cho said in an analysis posted on the website of his institute on Wednesday. That, Mr. Cho added, could leave Mr. Kim vulnerable to popular uprisings amid continuing economic hardships because he might not be able to rely on the kind of support the military provided for his father when he led his country through the great famine of the 1990s.