V for venom: 6 questions about nerve agent used in Kim Jong-nam death

Malaysian police say VX nerve agent a weapon of mass destruction was used to kill the half-brother of North Korean leader Kim Jong-un, prompting concerns about how the banned chemical weapon was obtained and used.

Police say two women approached the victim in a crowded airport terminal in Kuala Lumpur and wiped a liquid on his face on Feb. 13. He sought help at the airport but died on the way to the hospital.

• AS IT HAPPENS The world's 'most toxic nerve agent' suspected in Kim Jong-nam's death
• Nerve agent used in murder of Kim Jong-nam, Malaysia says
• Kim Jong-un's half-brother assassinated by North Korea agents, South alleges

Pyongyang has denied responsibility for the attack on Kim Jong-nam, who had openly called for political reform in North Korea and lived in exile in Macau.

What is VX nerve agent?

The "V" in VX stands for "venom," a recognition of this agent's potency and its ability to penetrate the skin, according to the National Academies of Sciences, Engineering and Medicine. It is a clear liquid with the viscosity of motor oil.

A tiny drop of the odorless liquid on the skin may cause convulsions, paralysis, and respiratory failure within minutes of application, according to the U.S. Centers for Disease Control and Prevention.

How powerful is it?

Extremely powerful, in fact, VX nerve agent is the deadliest of its kind ever produced, according to the New York-based Council on Foreign Relations.Treatment is possible, according to the CDC which says that an antidote, if administered immediately, can save a person's life.

Who created it?

A British chemist named Ranajit Ghosh first synthesized the agent in the early 1950s while doing research on pesticides. The compound was too potent for the commercial market but the British government later recognized its potential warfare properties. VX was also shared with the U.S. army.

Has it ever been used before?

Yes, the Japanese cult Aum Shinrikyo used VX in a series of attacks in 1995. Cult members confessed to carrying syringes filled with VX to spray three people. One person died in the attacks. The cult later used sarin, a nerve gas, in a Tokyo subway, killing 13 people and injuring more than 6,000.

Iraq is believed to have dropped VX, along with other chemical weapons, from planes on the Kurdish city of Halabja. Local aid organizations estimated as many as 6,800 people died in the 1988 attack.

Who has it?

The U.S. and Russia are the only two countries to state they have stockpiles of VX, though others are believed to have the capability to produce the nerve agent. VX is banned under the UN Chemical Weapons Convention.

North Korea says it does not have any chemical weapons an assertion South Korea rejects. The South Korean defence ministry in 2012 estimated Pyongyang has as much as 5,000 metric tons of chemical weapons.

What's different about the attack on Kim Jong-nam?

Observers suggest that if North Korea was behind Kim Jong-nam's death, this represents a brazen attack on the part of Kim Jong-un, who also recently test-fired a ballistic missile into the Sea of Japan.

Kim Dae Young, a South Korean military expert, said if North Korea was responsible it shows a new level of skill in deploying complex chemical weapons.

"They probably conducted a lot of tests to come up with a perfect amount that would kill Kim Jong-nam, but not harm the assailants or anyone else nearby in a crowded airport," Young told Reuters.