Malaysian authorities said preliminary laboratory tests identified VX nerve agent on the eyes and face of Kim Jong-nam, the estranged older half brother of North Korean leader Kim Jong-un, following his killing at Kuala Lumpur International Airport on February 13. Two women allegedly wiped chemicals on his face while he was waiting for a flight to Macau, where he lived with his family. Kim sought help from airport staff, suffered convulsions and died while being taken to hospital. He was travelling under the passport name Kim Chol.

VX is an extremely potent chemical warfare agent banned under the 1993 Chemical Weapons Convention. An oily, largely odourless liquid, it disrupts nerve signalling and can kill through very small amounts absorbed through the skin. Exposure can cause vomiting, confusion, seizures, paralysis and death. Its identification raised questions about how it entered Malaysia and why such a dangerous substance was used in a busy public airport. Japanese cult Aum Shinrikyo previously used homemade VX against three people in 1994 and 1995, killing one.

The finding also prompted concern about possible contamination at the airport, in the ambulance and at medical facilities. VX can remain hazardous for an extended period, yet the airport had reportedly operated for about 11 days without decontamination. Police subsequently said cleaning was being undertaken or planned. No additional illnesses were reported among passengers, airport workers or medical staff, although police said one of the two female suspects had experienced vomiting.

Investigators alleged that the women, one Vietnamese and one Indonesian, knowingly handled poison and were instructed to wash their hands after the attack. Relatives and acquaintances maintained that they must have been deceived. Toxicologists questioned how the suspects could handle VX without severe injury; possible explanations, including receiving antidotes, remained speculation. Authorities detained the women and a North Korean man and sought several other North Koreans, including an embassy official and an employee of Air Koryo.

Suspicion centred on North Korea, which denied involvement and accused Malaysia of fabricating evidence under South Korean influence. Pyongyang challenged the investigation and post-mortem examination, blamed Malaysia for the death and did not publicly acknowledge the victim as Kim Jong-nam. Malaysia sought access to a senior North Korean embassy employee, while its foreign minister warned that the North Korean ambassador could be expelled over his accusations. The dispute strained previously friendly relations between the two countries.

Kim Jong-nam, the eldest son of former leader Kim Jong-il, had once been considered a possible successor. He fell from favour, notably after being caught entering Japan on a false passport in 2001, and later criticised North Korea’s policies and hereditary leadership while living abroad.

The case renewed scrutiny of North Korea’s suspected chemical weapons programme. North Korea has not signed the Chemical Weapons Convention. Estimates cited in the reports placed its chemical weapons stockpile at 2,500–5,000 tonnes and annual production capacity at roughly 4,500 tonnes, potentially rising to 12,000 during a crisis. Its suspected arsenal includes mustard, phosgene, sarin and VX, raising concerns about both military use on the Korean Peninsula and covert attacks overseas.