Top 5 deadliest chemical weapons ever created

In July 2023, the United States destroyed its last chemical weapon, an M-55 rocket containing a Sarin gas payload. It was the culmination of decades of hard, careful work to end an era of devastating, deadly and inhumane warfare. Before the implementation of the 193-country Chemical Weapons Convention (CWC) began, however, countries began a frightening arms race with the goal of creating the deadliest chemical weapons ever conceived.

Only three countries - North Korea, Egypt, and South Sudan - have yet to sign or ratify the Chemical Weapons Convention. Israel has signed but not ratified, meaning any of these four countries could still be harboring some of these deadly substances. While not every agent listed by the CWC is only used in chemical warfare, its Schedule 1 substances have little to no use outside of killing people.

Novichok and its five known variants were first developed during the Cold War for use by the Soviet Union. Novichok agents began making international headlines once more the past few years because they were used in assassination attempts on Sergei Skripal, a former Russian Intelligence Officer and Alexei Navalny, a prominent Russian dissident.

The only reason the West knows anything about Novichok is because a former chemical weapons scientist from the former USSR divulged the information. First developed in the 1970s, Novichok was designed to penetrate NATO protections while being 100% fatal. Since it’s 10 times more potent than VX (one of the nerve agents, which are the most toxic of the known chemical warfare agents), it usually is. What we know for sure is they are a combination of safe compounds that are brought together right before they are used, making the agents hard to track – and no one knows what those binary precursors are.

Also known as “Venomous Agent X,” VX was designed to be stable, persistent, and deadly. Originally developed by German scientists in the 1930s, it can be absorbed through the skin or inhalation, and causes severe convulsions, paralysis and asphyxiation after exposure to tens of milligrams. Death comes within minutes. Moreover, it’s highly resistant to any known poison antidotes.

VX has been used by Cuban forces against Angolan insurgents in Africa in the mid-1980s. Saddam Hussein also used VX in his attacks on Kurdish minorities in northern Iraq in his al-Anfal campaign. Kim Jong-nam, half-brother of North Korean leader Kim Jong-un, was attacked and assassinated with VX at an airport in Malaysia.

Also developed by Nazi scientists, cyclosarin is identified by the United Nations solely as a weapon of mass destruction. Odorless and colorless, cyclosarin can be shipped as a binary munition, meaning its precursor agents are stable and safe. When combined, however, the cyclosarin is five times deadlier than sarin gas and not easily dispersed or evaporated. Victims will convulse uncontrollably within seconds of exposure before becoming totally paralyzed, leading to respiratory failure and death in less than a minute.

Since cyclosarin is so costly to produce, only Saddam Hussein ever used cyclosarin in warfare, during the decade-long Iran-Iraq War.

Soman is another Nazi-made gas that is delivered in the form of a gas, since the agent must be activated with heat. At low levels, victims begin to drool uncontrollably, feeling fatigue, nausea and vomiting. Sweating, weakness and confusion follow before the victim can no longer control their bowel movements or urination. Larger doses cause convulsions and paralysis, followed by asphyxiation within minutes of exposure.

Sarin gas made its biggest headlines in 1995 when the Japanese cult movement Aum Shinrikyo used it on a Tokyo subway, killing 14 people and injuring another 6,200. Most recently, sarin was used by the Syrian regime under Bashar al-Asad against rebels in the country’s Idlib Province.

Like the other nerve agents on this list, gas-activated sarin causes convulsions and paralysis but can kill within seconds of exposure. It’s one of the deadliest chemical agents ever designed, 26 times deadlier than cyanide. But unlike the other nerve agents on the list, it can be reversed by a quick reaction with an antidote.