The assassination of Kim Jong-un's half brother Kim Jong-nam was reportedly carried out in Malaysia using VX, a nerve agent that has been well-characterized as a potent chemical weapon for decades. The delivery mechanism was allegedly via skin exposure as the assassin rubbed the substance into Kim Jong-nam's face.
VX belongs to a class of banned chemical warfare agents that includes sarin, well known after its use in the Aum Shinrikyo (they also experimented with VX) Tokyo Subway attacks in the 1990s, and all of these agents act to interfere with neurotransmission -- the way nerves speak to each other and to muscles. Specifically, these agents increase the amount of the neurotransmitter acetylcholine leading to predictable effects that medical students always memorize. Salivation, lacrimation, urination, diarrhea, vomiting, small pupils (miosis), and a slow heart rate are all part of what is known as a cholinergic syndrome. If not reversed, it is fatal.
The most potent of nerve agents, just 10 milligrams of this tasteless odorless liquid is enough to prove fatal.
Atropine, a very commonly used medication in hospitals, is one of the antidotes that can reverse the symptoms. This is given in conjunction with another medication called pralidoxime.
This event underscores that chemical -- and likely biological weapons -- remain major threats and rogue nations, where individual rights are non-existent, remain a threat that merit preparing for. During the coming days, it will be critical to confirm the manner of death of Kim Jong-nam.