Kim Jong-nam, the estranged half-brother of North Korean leader Kim Jong-un, died after an apparent nerve-agent attack at Kuala Lumpur International Airport on February 13. Malaysian investigators said two women approached him in the check-in hall and wiped a substance on his face as he waited for a flight to Macau, where he lived with his family. He sought help from airport staff, suffered convulsions and died on the way to hospital.

Malaysia’s police chief, Khalid Abu Bakar, said preliminary toxicology tests detected VX nerve agent in swabs from Kim’s eyes and face. VX is a highly toxic chemical warfare agent banned under the 1993 Chemical Weapons Convention. It can enter the body through the skin, eyes, lungs or digestive system, disrupting nerve signals and causing symptoms ranging from vomiting and blurred vision to seizures, paralysis and death. Even a very small amount can be lethal.

The reported use of VX raised questions about public safety and how the substance entered Malaysia. The oily agent can persist on surfaces, yet the airport had gone about 11 days without decontamination. Authorities said they intended to clean areas visited by the suspects. Police reported that the two women had experienced vomiting, but no passengers, airport workers or medical staff who treated Kim were reported to have fallen ill. Experts also questioned how the women could have handled VX and survived; investigators said they had been instructed to wash their hands after the attack.

Malaysia detained the two women, one Vietnamese and one Indonesian, along with a North Korean man, and sought several other North Koreans, including an embassy official. Malaysian authorities said North Korean agents were involved, while relatives and acquaintances of the women maintained that they had been duped. North Korea denied responsibility, challenged Malaysia’s investigation and accused its government of fabricating evidence. The dispute strained relations between the countries, and Malaysia warned that it could expel the North Korean ambassador over his statements.

Kim Jong-nam was the eldest son of former North Korean leader Kim Jong-il and had once been considered a potential successor. After being caught trying to enter Japan on a false passport in 2001, he lived largely abroad and became a critic of North Korea’s policies and dynastic succession. He was travelling under the name Kim Chol; North Korea did not acknowledge that the dead man was Kim Jong-nam.

North Korea has not signed the Chemical Weapons Convention and is believed to possess a large chemical weapons stockpile, estimated by South Korea at 2,500 to 5,000 tonnes. Reports cited in the passages also estimate substantial production capacity and list VX among the agents the country may possess.