KIM Jong-un wanted to assassinate his half-brother in the most "gruesome" and public way possible earlier this year to "horrify the rest of the world" and instil fear among his doubters, a new report claims.

Fox News reports the daring assassination of Kim Jong-nam in February undertaken by two prostitutes in Malaysia's Kuala Lumpur airport has mostly been shrouded in mystery, with few reports from South Korean media speculating why the estranged half-brother of the North Korean despot was killed.

A South Korean spy agency initially said the death was part of the leader's five-year plot. A Korea University professor investigating the assassination - and who previously led a research arm with South Korea's intelligence agency - told GQ on Monday it was all "part of a master plan."

Kim Jong Nam, 46, was targeted Monday, Feb. 13, 2017, in the Kuala Lumpur International Airport, Malaysia, and later died on the way to the hospital.
Kim Jong Nam, 46, was targeted Monday, Feb. 13, 2017, in the Kuala Lumpur International Airport, Malaysia, and later died on the way to the hospital. AP Photos - Shizuo Kambayashi

"From the moment Jong-nam left Macau, the North Koreans tailed him," Nam Sung-wook told GQ.

"They had a group on his airplane. As soon as he arrived at the airport in Kuala Lumpur, another group followed him. They kept that surveillance up while he slept. Even as Jong-nam entered the terminal, he was shadowed."

Several reports claimed the assassination attempt was sloppy work by the North Korean government. The women were clearly visible on CCTV walking up to Kim Jong-nam and smearing the banned VX nerve agent on his face. The North Korean agents accused of co-ordinating the attack never hid their faces either.

Nam said people shouldn't dismiss this as some bad planning on Kim's part.

"Pyongyang wanted to send a worldwide message by murdering Kim Jong-nam in this gruesome, public way," Nam said.

"Pyongyang wanted to horrify the rest of the world by releasing a chemical weapon at an airport."

He added: "Jong-un wants to reign a long time and negotiate as a superpower. The only way to do that is to keep the world in fear of his weapons. He has a grand design, and this is part of it."

Two women, identified as Siti Aisyah and Doan Thi Huong, are the only two people in custody and are charged in Kim Jong-nam's death. Both worked as escorts and claim they were duped into thinking they were playing a harmless prank for a television show. They face the death penalty if convicted.

Alleged assassin Doan Thi Huong.
Alleged assassin Doan Thi Huong. Facebook

Reports have since emerged saying Kim Jong-nam was being positioned to lead the North Korean government-in-exile. He also may have appeared as a threat to the current North Korean leader because he was older.

A report by Japanese magazine Nikkei Asian Review also claimed Kim Jong-un had his uncle, Jang Song Thaek, executed after uncovering an alleged coup plot co-ordinated with the Chinese government.

North Korea refuses to accept Kim Jong-nam as the half-brother of Kim Jong-un and believes a heart attack was the true cause of death. The regime also accused the Malaysian government of working with South Korea and other "hostile forces" to blame them for the assassination.

Kim Jong-nam was living abroad when he was killed. He was arrested in 2001 while trying to sneak into Japan to visit Tokyo Disneyland.

There were two other attempts to assassinate Kim Jong-nam before his strange death, once in 2010 and another in 2012, GQ reported. Eventually, the regime also cut his funds, leaving him begging his family to not punish him because he and his family had "nowhere to hide."