[3] Hyon was promoted to the rank of Vice Marshal (차수) of the KPA in July 2012, two days after Chief of the General Staff Ri Yong-ho was relieved of his duties.

South Korea's National Intelligence Service initially reported on May 12, 2015, that Hyon was purged and publicly executed near the end of April 2015 at Kanggon Military Training Area near Pyongyang.

[13][14] It was reported that he was executed – with an anti-aircraft gun – for insubordination and sleeping during formal military rallies, in particular during an event in late April 2015 attended by Kim Jong Un in which Hyon was captured on video napping.

According to analysts interviewed by BBC News, while reassigning officials was commonplace in North Korea, the execution of a figure as close to Kim Jong Un as Hyon was surprising, and could give cause to concern for the country's stability.

[18] In July, official North Korea media named Pak Yong-sik as the armed forces minister, but did not report Hyon's removal.

[20] In April 2015, the US-based Committee for Human Rights in Korea released satellite imagery showing a shooting range lined with anti-aircraft guns apparently primed for an execution last October.