What is VX, the chemical weapon that killed Kim Jong Un's half-brother?

What is VX, the chemical weapon that killed Kim Jong Un's half-brother?
Source: Getty Images
Source: Getty Images

Kim Jong Nam, the older half-brother of North Korean supreme leader Kim Jong Un who was assassinated on Feb. 13 in Kuala Lumpur airport under bizarre circumstances, was reportedly killed with the highly deadly nerve agent VX, Malaysian police said Friday. 

VX is one of the most toxic chemical warfare agents in existence, internationally banned by the Chemical Weapons Convention. It is a tasteless and odorless amber-colored, clear and oily liquid, making it easy to go undetected.

Swabs taken from 46-year-old Kim's eyes and face as part of the autopsy revealed the presence of VX, authorities said. Two women smeared a substance on the victim's face as he waited to board a flight — Kim died shortly after while en route to the hospital. 

Exposure to VX — through skin or eye contact, inhalation or ingestion — can kill someone within minutes. "As little as one drop of VX on the skin can be fatal," the Centers for Disease Control and Prevention explain. 

It works by inhibiting an enzyme that allows glands and muscles to relax. With insufficient levels of this enzyme, the glands and muscles cannot stop being stimulated, ultimately tiring out and unable to support breathing.

Known chemically as S-2 Diisoprophylaminoethyl methylphosphonothiolate, VX is classified as a weapon of mass destruction by the United Nations.

Russia and the United States are the only two countries to disclose having VX stockpiles, some of which the U.S. has exterminated. However, international intelligence suggests it is among Syria's stockpile of chemical weapons. 

The U.S. and South Korea strongly suspect Kim Jong Un ordered the assassination of his half-brother, the former heir apparent to the North Korea's ruling dynasty. North Korea denies these allegations.