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Members of the youth wing of the National Front, Malaysia’s ruling coalition, hold placards during a protest at the North Korea embassy following the murder of Kim Jong-nam in Kuala Lumpur. Athit Perawongmetha/Reuters

Malaysia says Kim Jong-nam was killed with a chemical weapon – here’s what you need to know

A preliminary report from Malaysian authorities has found that Kim Jong-nam, the half-brother of North Korean dictator Kim Jong-un, was killed by the banned nerve agent VX.

He died on his way to hospital from Kuala Lumpur airport on February 13 2017. It’s claimed that two women, who have now been detained, rubbed the chemical on his face.

We asked a pharmacologist to explain what the nerve agent involved is and how it works; and an expert in international law to examine the implications of an assassination using a banned chemical weapon on foreign soil.

What is VX nerve agent?

Chemical warfare weapons act on the nervous system (hence the name nerve agents), typically the nerves that control breathing. They act on the cholinergic nerves generally, which control the diaphragm.

Kim Jong-nam arrives at Beijing airport in 2017. Kyodo/Reuters

The VX nerve agent inhibits the enzyme acetylcholinesterase, which breaks down the neurotransmitter acetylcholine secreted by the cholinergic nerves. This results in more acetylcholine, which overstimulates the tissues, resulting in respiratory paralysis and death.

It is similar to but more powerful than sarin gas, which was used in the Tokyo subway attacks in 1995.

Only very little of a nerve agent is needed to kill someone, and it works very fast. The speed of death depends on mode of delivery. A nerve agent works faster if it goes directly to the respiratory system, but 10 milligrams on the skin will kill you.

Originally developed from a class of organophosphate pesticides that were abandoned as too toxic, the by British and US military agencies subsequently developed the VX nerve agent as a chemical warfare weapon.

Various governments stockpiled it as a chemical weapon, but stocks are being destroyed worldwide as part of the Chemical Weapons Convention. Saddam Hussein was thought to have used the toxin and it’s suspected Syria may have stockpiles, but the former USSR and the US are the only countries that have admitted to having VX or similar nerve agents. American stores were all destroyed by 2012.

There’s no clear evidence of it being used militarily, but Japanese cult Aum Shinrikyo used it to attack people in Osaka in December 1994 (as opposed to their sarin gas attacks on the Tokyo subway).

Japan’s Prime Minister Shinzo Abe offers flowers to victims of the sarin poison gas attack. Kyodo/Reuters

What does international law say?

The VX nerve agent is banned under international law because it’s a chemical weapon as defined in the Chemical Weapons Conventions. Such weapons were banned under international law for a number of reasons.

Chemical weapons are, by nature, indiscriminate – it’s very hard to use them in a way that targets only combatants (people directly participating in hostilities) and spares civilians, which is a fundamental rule of the law of armed conflict.

Even if you could use chemical weapons in a discriminate manner, they would still be illegal under the international law principle that prohibits means and methods of warfare that cause unnecessary suffering and superfluous injury, that is, when the injury or suffering caused is out of proportion to the military advantage sought.

While a number of countries are known or suspected to have VX in their possession, there’s no evidence that a state has employed it in armed conflict, or in any other context. North Korea is not a party to the Chemical Weapons Conventions.


Malaysia and the international community as a whole are somewhat constrained to act against North Korea for its use of VX nerve agent to kill Kim Jong-nam. The Malaysian authorities are, of course, perfectly entitled to prosecute the perpetrators. But whether the international community could do anything to North Korea itself is a bit more problematic.

First, it would have to be proved that the perpetrators were acting on instructions from North Korean authorities, or that their acts were somehow attributable to the North Korean government. Only then would the acts of the individual perpetrators be considered acts of the state.

The use of this chemical weapon is internationally prohibited, but the chances of being able to bring North Korean authorities before an international criminal tribunal, or to bring a suit against North Korea in the International Court of Justice, are essentially non-existent.

The only option would be for a resolution to be passed in the UN General Assembly or the Security Council, or both, condemning the use of chemical weapons in violation of the treaty. Another option is imposing sanctions against North Korea in addition to the ones that already exist.

Any country that maintains diplomatic relations with North Korea, such as Malaysia, or treaty arrangements could potentially be entitled to take action. It could expel North Korean diplomats, or withdraw its own ambassador from North Korea.

Whether it’s legal for a country to have someone killed on foreign soil as appears to have happened in this case is very complicated under international law. Broadly, it can be legal in a couple of very limited circumstances.

It’s allowed if the targeting state is at war with the targeted state (and the person who is killed is a citizen of the targeted state), and the person being targeted is a lawful target under the international law of armed conflict because that person is a member of the armed forces or is otherwise directly participating in the armed conflict.

Second, if the targeted person is about to carry out an armed attack on the targeting state, international law on the use of force says it’s lawful to target that person to stop them carrying out an imminent attack.

Kim Jong-nam’s half-brother Kim Jong-un is the dictator of North Korea. KCNA/Reuters

Having said that, neither of those scenarios seems to be at play here – the two women arrested for carrying out the attack are an Indonesian national and one carrying a Vietnamese passport.

Neither of those countries is at war with North Korea, so the first scenario is out.

The second scenario also doesn’t seem relevant as there’s no evidence to suggest that Kim Jong-nam was about to launch an armed attack against Malaysia, Indonesia or Vietnam necessitating the use of lethal force to prevent it. This appears to be a political assassination, not a legally justifiable act of self-defence or use of lethal force in a situation of armed conflict.

The only similar recent example that comes to mind is the assassination of a Hamas agent in Dubai in 2010, allegedly by the Israeli Mossad agency. That was a case of a person being killed on foreign soil, seemingly by a state government agency.

The international response ranged from condemnation of the act and expulsion of Israeli diplomatic agents from countries that had been subject to passport fraud in the process, including Australia, as those responsible for that attack were carrying fake documents from various states.

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