Was it a poorly executed assassination or did North Korea want to showcase its stockpile of banned chemical weapons?
The use of the highly toxic VX warfare agent to kill the estranged half brother of North Korea's leader has raised questions about Pyongyang's real motives in one of the strangest killings the world has seen.
Some say North Korea, in allegedly bringing a U.N.-classified weapon of mass destruction to kill a man at a busy international airport, intended to show the world what it can do with chemical weapons, which are easily forgotten amid concerns about the country's advancing nuclear missile technologies.
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But other experts believe it's unlikely that North Korea wanted VX to be discovered. There's no reason for Pyongyang to risk taking another hit when it's already under heavy international sanctions over its nuclear program. It's also doubtful that the country would be suddenly willing to showcase its chemical weapons as a deterrent when it has never acknowledged their existence, the experts say.
The use of VX as a murder weapon is not unprecedented, a Japanese doomsday cult killed one person with it in the 1990's. The same group later used sarin gas, a similar but less deadly nerve agent, to attack the Tokyo subway in 1995 - killing 12 people.
What is VX?
VX nerve agent was used to kill the estranged half-brother of North Korean leader Kim Jong Un in a bizarre murder in Malaysia last week, police said on Friday.
Kim Jong Nam was killed on Feb. 13, shortly after being assaulted at the airport in the Malaysian capital, Kuala Lumpur, by two women who wiped the chemical on his face as he prepared to board a flight to the Chinese territory of Macau.
South Korean and U.S. officials have said they believe North Korean agents assassinated Kim Jong Nam. He had been living with his family in Macau under Beijing's protection and had spoken out against the North Korean regime.
Malaysian police were investigating whether the VX - which is believed to be the most toxic known nerve agent and is banned globally except for research - was brought into the country or made there.
"If the amount of the chemical brought in was small, it would be difficult for us to detect," police chief Khalid Abu Bakar told reporters.
VX is tasteless and odorless, and is outlawed under the Chemical Weapons Convention, except for "research, medical or pharmaceutical purposes". It can be manufactured as a liquid, cream or aerosol.
Experts say it has no commercial uses.
"This is not something you make in a kitchen lab. This is something that is made in a very sophisticated chemicals weapons lab," said Bruce Bennet, a senior defense researcher at the California-based RAND Corporation.
North Korea is believed to have the world's third-largest stockpile of chemical weapons, according to the Nuclear Threat Initiative project, which analyses weapons of mass destruction.
VX in liquid form can be absorbed into the body through skin or eye contact and does not evaporate easily.
How could North Korea use VX?
If North Korea is behind this murder, experts say there's still cause for concern, CNN reported over the weekend.
"On the back of North Korea's recent advances in nuclear and missile capabilities, this sends a big signal to the international community about its military reach," says East Asia Security Policy Analyst, Corey Wallace.
"This goes beyond the more traditional question of 'deterrence' against foreign enemies for which North Korea's nuclear weapons program is arguably being developed," he says.
VX is most deadly when dispersed over a large populated area, with the potential to kill en mass. North Korea's willingness to deploy the weapon overseas could be a watershed moment for the rogue regime as it shows a new willingness (and or recklessness) to go on the offense with unconventional weapons.