He was charged with treason after dozing off at a military rally on April 24-25, “talking back” to the young ruler and failing to follow and complaining about his instructions, said Reps. Lee Cheol-woo and Shin Kyoung-min, members of the National Assembly’s intelligence committee, after the session.

Hyon, who was promoted to the rank of vice marshal in 2012, is the latest victim in an ongoing string of slayings Kim has been engaging in to cement his power, according to the NIS. The military leader appears to be the highest executive to be executed since Jang Song-thaek, was killed in December 2013. Jang was Kim’s uncle and vice chairman of the powerful National Defense Commission, and was once dubbed the country’s second most influential man.

“Unlike previous purges such as of Jang and former military Gen. Staff Chief Ri Yong-ho, Hyon’s execution was swiftly carried out, within three days after his arrest, without the party politburo’s decision-making process or a trial,”the NIS was quoted as saying by lawmakers, adding that details of the reason behind the purge need further confirmation.

Yet the agency dismissed as “groundless” a recent news report that Kim Kyong-hui, Jang’s widow, was poisoned to death a year ago. Speculation persists over her whereabouts, as she has made few public appearances since her husband’s death, and is known to have been receiving treatment for an illness in Singapore and elsewhere.

Pyongyang has also killed other military and party aides over the past six months, the NIS noted, including Ma Won-chun, a senior NDC official; Gen. Pyon In-son, head of operations in the Korean People’s Army; and Han Kwang-sang, a director of the finance department at the ruling Korean Workers‘ Party.

They are three of the at least 15 senior officials who the agency said late last month were executed this year, in addition to the confirmed 41 cases last year. The list includes a vice forestry minister accused of complaining about reforestation policy and four artists of the Unhasu orchestra, a top music company in the North, who were caught up in a sex scandal.

By Shin Hyon-hee (heeshin@heraldcorp.com)