Kim Jong Un
North Korean leader Kim Jong-Un supervised a meeting of the Political Bureau of the Central Committee of the Workers' Party of Korea in Pyongyang, 18 February 2015Reuters via KCNA

North Korean defence minister Hyon Yong Chol has reportedly been executed for showing "disrespect" and falling asleep during a military drill.

The method chosen for his execution was gruesome, with Hyon reportedly killed by anti-aircraft guns, watched by hundreds of spectators, South Korean intelligence told lawmakers.

Satellite images seem to confirm the claims, picking up what appeared to be anti-aircraft guns facing a close target on the Kanggon army training area, surrounded by military vehicles and a viewing platform.

It comes amid a purge of party officials, as dictator Kim Jong-Un employs terror to maintain complete authority over the pariah state, and cow potential rival power bases.

This year alone, North Korea has executed 15 officials, the New York Times reported, citing South Korean intelligence.

Among those killed this year on Kim's orders are a vice minister, who was executed in January after complaining about Kim's forestation policy. Another minister was killed after objecting to Kim's decision to change the design of a roof of a building under construction in Pyongyang. Four members of an orchestra which Kim's wife once performed in who were killed on espionage charges in March.

Penchant for gruesome executions

Kim has gained a reputation as a dictator arguably more unstable and brutal than his father, with a penchant for gruesome execution methods. However with foreign media banned from the state, reports of lurid executions can be difficult to verify.

Rumours of execution by ravenous dogs emerge

Jang Song Thaek was described as the second most powerful figure in North Korea and was married to Kim's aunt. In a purge of senior party figures, Jang was accused of pursuing a "decadent capitalist lifestyle", squandering state funds, and plotting to overthrow Kim.

After a show trial before a military tribunal, Jang was executed by firing squad in December 2013.

In the wake of his death, reports surfaced that Jang had been killed after being locked in a cage with starving dogs. The rumours were exposed as a spoof, which originated on a Chinese microblogging site.

Poison

Kim Kyong Hui, Jang's wife and Kim Jong-Un's aunt, reportedly died of a stroke in May 2014.

However, a defector from the secretive totalitarian state claims that she was poisoned on the direct order of her nephew after complaining about her husband's execution.

Machine gun

Up to 30 of Jang's aides were publicly executed following his arrest - though not by rifle, but by four-barrelled machine guns.

Flame thrower

In April 2014, Security Minister O Sang-hon, was killed in the purge of Jang's allies. He was allegedly burnt to death by a flame thrower on corruption and racketeering charges.

Explosives

A vice minister in the army was reportedly executed with a mortar round after reportedly going on a drinking bout during the period of official mourning after the death of Kim's father Kim Jong Il in 2011.

He was ordered to stand on a spot targeted by a mortar round and "obliterated," reported South Korean media.