Kim Jong-un’s decision to carry out a fourth nuclear test regardless of international sanctions has drawn criticism from colleagues in the ruling party, sources inside the country claim.

Speaking under the condition of anonymity from Pyongyang, a source said party cadres had described the nuclear test as a sign of the leader’s “irresponsible and immature personality”.

High-ranking personnel in the North Korean regime have been talking about about Kim’s “aggressive personality” since he was a child, the source added, although the claim are impossible to independently verify.

“If Kim had been a bit more of a nerd he never would have been selected as Kim Jong-il’s trainee for the role of successor.”

Another source, speaking from North Hamgyong Province, corroborated the claims, and said evidence of Kim’s erratic behaviour could be seen in December in the last-minute cancellation of the Moranbong girls’ band tour of China.

The young leader was also reported to have suddenly called off UN secretary general Ban Ki-moon’s visit just a day before the scheduled date in May.

“Kim Jong-un has been treated like a king since he was a child and has a difficult time hearing other people’s points of view,” the second source claimed.

“Nervous about what he might do, both party cadres and citizens tread lightly around him.”

A Japanese sushi chef, under the pen name Kenji Fujimoto, wrote about his experiences with Kim in his memoir, Kim Jong-il’s Cook.

He prepared meals for Kim’s father the former leader from the late 1980s until fleeing Pyongyang in 2001, and described the current leader as “tempestuous” even at an early age, and “hating to be treated like a child”.

“If you called him ‘young commander’, he would get very angry,” said Fujimoto in the 2003 book.

A version of this article first appeared on Daily NK – part of the Unification Media Group