Toxicology tests show the estranged half-brother of North Korean leader Kim Jong-Un was murdered using VX nerve agent.

So what exactly is the deadly chemical used to kill Kim Jong-Nam at Kuala Lumpur airport in Malaysia?

:: What is VX?

The official name of the highly toxic chemical is: S-2 Diisoprophylaminoethyl methylphosphonothiolate. But it is usually goes by the American code name of VX, with the 'V' standing for venom.

WMD used to kill North Korean leader's half-brother

:: What does it look like?


The clear, amber coloured poison can be made as a liquid, cream or an aerosol. It is both tasteless and odourless.

However, due to its oily nature - rather like motor oil - it doesn't mix well with water.

:: How powerful is it?

It is about 100 times more potent than the nerve agent Sarin.

About 0.01g - less than a drop - on the skin is enough to disrupt the body's nervous system and will kill a person in less than 15 minutes.

:: What does it do to you?

The toxin sparks respiratory collapse and heart failure, with effects kicking in within seconds or over hours depending on the dose.

Initial symptoms are confusion, possible drowsiness, headache, nausea, vomiting, runny nose and watery eyes.

:: Toxic airport checks after Kim Jong-Nam murder

These then give way to convulsions, seizures, loss of consciousness and paralysis, and eventually death.

After seeking help from airport staff, Kim Jong-Nam suffered a seizure and died on the way to hospital.

Image: Kim Jong-Un's half-brother, Kim Jong-Nam, pictured in 2010

:: Is there a cure?

Yes - the drug Atropine is an antidote to VX and can be administered by injection - but it has to be applied quickly.

:: Why hasn't it poisoned the attackers too?

The two female attackers captured on camera appear to wipe the face and eyes of the victim with their bare hands.

Officials said immediately following the attack they then washed their hands to remove the substance, although police have confirmed that one of the women later became ill, vomiting while in custody.

:: Could the Kuala Lumpar airport still be dangerous?

Due to the thick and oily nature of the substance, it can take days or even weeks to evaporate.

This has raised fears the public could be in danger from possible contamination in the area of the attack, as well as anywhere that Kim came into contact with after being poisoned.

:: History

The chemical was invented in Britain during the 1950's by a chemist called Ranaji Ghosh who was working for Imperial Chemical Industries.

Inspired by a commercial pesticide, it was further tested by the British military, before being passed to US counterparts, who began full-scale production of VX in 1961.

:: Can it be weaponised?

Yes. VX was manufactured for chemical warfare and has been listed by the UN as a weapon of mass destruction.

The US government's Centers for Disease Control and Prevention (CDC) describes it as the "most potent" of all nerve agents.

:: Has it been used to kill anyone before?

In 1969, 23 soldiers and one civilian were sent to hospital after the VX nerve agent stored in a US military base in Okinawa, Japan, leaked. The incident provoked widespread outrage in the country.

VX was used by Japan's Aum cult in the 1995 murder of an office worker in Osaka, and in the attempted murder of two other people.

Until Kim was attacked at Kuala Lumpur airport earlier this month, there had been no other recorded cases of VX being used as a method of assassination.

Image: VX is about 100 times more potent than sarin - less than one drop will kill you

:: So it is illegal?

Of course. The lethal nerve agent was banned under the 1993 Chemical Weapons Convention except for "research, medical or pharmaceutical purposes".

Russia and America are the only countries who have officially admitted to owning VX stockpiles. Under international law, states should not manufacture it and should destroy their supplies.

Does North Korea have VX?

Yes. North Korea never signed the 1993 treaty (along with Egypt and South Sudan), and has spent decades developing a chemical weapons programme.

Experts have said North Korea has up to 5,000 tonnes of chemical weapons stockpiled, including a supply of VX, causing much concern among the international community.