Malaysian police have revealed that the nerve agent VX was used to kill Kim Jong-nam when he was attacked at Kuala Lumpur’s international airport.

What is VX?

VX is the deadliest nerve agent ever created. Just one drop containing 10 milligrams of VX, absorbed through the skin, is enough to cause “fatal disruption of the nervous system”, according to the Council on Foreign Relations.

It is 100 times more deadly than the nerve gas sarin, which was used by members of a Japanese doomsday cult in their deadly 1995 attack on the Tokyo subway.

VX, whose chemical name is O-ethyl S-diisopropylaminomethyl methylphosphonothiolate, is hard to detect. It is a clear, tasteless and colourless liquid with a consistency something like engine oil.

So potent is VX that the UN classifies it as a weapon of mass destruction. The CDC, the US government’s top public health agency, says its only known use is in chemical warfare.

How does it affect the body?



VX works by penetrating the skin and disrupting the transmission of nerve impulses. Exposure to VX may result in convulsions, loss of consciousness, paralysis and fatal respiratory failure .

The “V” in VX stands for venom, “a tribute to this compound class having high potency and a characteristic ability to penetrate the skin”, according to the National Academies website.



Hiroyuki Nagaoka, who was attacked with VX by members of a Japanese cult in 1995 (see below), described the experience to public broadcaster NHK.



Nagaoka said he was walking in Tokyo when a cult member sprayed the nerve agent on the back of his neck. Most of it was blocked by his jacket collar. “I had no idea what happened at that time,” he said.

He finished walking home but about half an hour later realised everything seemed to be oddly dark, an effect of the toxin causing his pupils to shrink. He started feeling hot and, sweating profusely, took off his clothes.

His wife later told him that he got down on all fours like an animal, twisting and scratching his neck and chest, before rolling on to his back in pain and losing consciousness.

He was rushed to a hospital for emergency treatment and was unconscious for several days. “I was saved by the collar of the jacket I was wearing,” he told NHK, adding that he still has numbness on the right side of his body and uses an oxygen tube inserted in his nostrils to assist his breathing.

It is thought possible to treat a VX attack with an injection of multiple antidotes, but the nerve agent works so quickly that a victim would have to be treated immediately to stand any chance of survival.



Raymond Zilinskas, who directs the chemical and biological nonproliferation programme at the Middlebury Institute of International Studies in California, said it seemed unlikely that VX was applied directly to Kim.

“Even if they [the suspected attackers] were wearing gloves, the fumes would have killed them,” he said. He suggested the suspects might have used a “binary concoction”, smearing two non-fatal elements of VX that mixed on the victim’s face.

What are its origins?

VX was first synthesised in the early to mid-1950s by Ranaji Ghosh, a chemist working for Imperial Chemical Industries in Britain. Its toxicity and physical properties were studied by the British military, which passed the formula on to the US military [PDF], according to the National Academies of Sciences, Engineering and Medicine in Washington. The US began full-scale production of VX in 1961.

The US army was involved in several controlled and accidental releases of VX gas. Iraq was reported to have produced more than 50 tonnes. Under Saddam Hussein, Iraq is thought to have used VX in a 1988 attack against the Kurds and during the Iran-Iraq war.

Who has VX?



The US and Russia are the only countries that have admitted owning VX stockpiles, but more countries are believed to hold it. The US destroyed a small portion of its stockpile under the Chemical Weapons Convention and there have been moves for Russia to follow suit.

According to a French intelligence assessment published in September 2013, Syria’s chemical weapons stockpile includes “several tens of tonnes” of VX.

Months before killing about a dozen commuters and severely injuring dozens more in Tokyo with sarin, another kind of nerve gas, in March 1995, the Aum Shinrikyo Truth cult tried VX on at least three victims, killing one, whom cult members believed was a police informant.

North Korea claims it has never had a chemical weapons programme. But in fact it is believed to possess between 2,500 and 5,000 tons – behind only the US and Russia – including VX, according to the Nuclear Threat Initiative.

“The South Korean government assesses that North Korea is able to produce most types of chemical weapons indigenously, although it must import some precursors to produce nerve agents, which it has done in the past,” the NTI said.



“At maximum capacity, North Korea is estimated to be capable of producing up to 12,000 tons [of chemical weapons]. Nerve agents such as sarin and VX are thought to be the focus of North Korean production.”