SEOUL-- North Korea is unlikely to stop its provocative acts unless its "hot-tempered and reckless" leader Kim Jong-un is eliminated, a security expert here said Wednesday.

Nam Sung-wook, a Korea University professor who formerly headed the Institute for National Security Strategy (INSS), said that the North's leader was described by witnesses as a hot-tempered and reckless person when young, which may have partly led to his current obsession with nuclear and missile programs.

"The latest development (North Korea's latest sixth nuclear test) is largely attributable to Kim's wild character. If Kim is not eliminated, this issue (the North's provocation) will persist," Nam told lawmakers of the main opposition Liberty Korea Party.

He made the remark based on analyses on North Korea made when he served as the head of the institute under Seoul's spy agency in 2008-2012.

North Korea conducted four out of six nuclear tests under the guidance of Kim Jong-un who assumed power in late 2011 after the sudden death of his father. The wayward regime is seeking to develop a nuclear-tipped intercontinental ballistic missile (ICBM).

As to the North Korean leader's character, Nam introduced a phone conversation between Kim and his girlfriend in Pyongyang while he spent his adolescence in Switzerland at the age of about 15.

"As Kim was smoking at a young age, his girlfriend advised him to quit smoking. Then, Kim exploded with foul language, which was quite shocking (to her)," he said.

Nam said he previously thought that if Kim rules the North, things would be very complicated.

"At that time, I wished my prediction would not be right. Unfortunately, however, it has come true," Nam said. "Any vague fear of Kim is not desirable. Likewise, any simple evaluation of Kim is a no-no."

Kim Jong-un is the third and youngest son of late former leader Kim Jong-il, who was believed to have started grooming his successor after he suffered a stroke in August 2008.

Kim Jong-nam, the first son, was once viewed as an heir apparent, but he had been living in foreign countries for years after apparently falling out of favor with his father for attempting to enter Japan with a fake passport in 2001. He was killed in February this year in Malaysia, in an assassination which Seoul links to the Pyongyang regime.

The second son Jong-chol suffered from an excess of female hormones after a car accident, Nam said.

Source: Yonhap News Agency