Chemical weapon

• 1. Introduction

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  Chemical weapons are among the few inventions humanity has consistently tried to ban before the full scale of their consequences was understood. In June 1925, diplomats gathered in Geneva to sign a treaty declaring that poison gases and biological agents were "justly condemned by the general opinion of the civilised world." And yet, decades later, an estimated 100,000 Iranian troops became casualties of Iraqi chemical weapons in a single war. What is it about these weapons that keeps drawing nations back, despite the horror, despite the treaties, despite the prosecutions? This documentary traces the answer through the laboratories where nerve agents were discovered, the conventions that tried to stop them, the seas where old stockpiles were quietly dumped, and the civil wars where they keep reappearing.

• 2. What Makes a Chemical Weapon

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  The Organisation for the Prohibition of Chemical Weapons defines a chemical weapon as any compound intended as a weapon, or its precursor, that can cause death, injury, temporary incapacitation, or sensory irritation through its chemical action. That definition is deliberately broad. Delivery systems, whether filled or empty, count as weapons themselves. So does a precursor chemical sitting in a drum.

  Lethal agents include nerve agents such as tabun, sarin, soman, VX, VR, and the Novichok family, alongside blister agents like mustard gas. Non-lethal agents include tear gases such as CS gas and pepper spray, as well as incapacitating agents like 3-Q/BZ. Some chemical weapons, notably VX, are persistent, lingering in an environment long after deployment. Others are highly volatile and disperse quickly.

  Binary munitions add a further wrinkle. They contain two isolated chemicals that remain inert until combined, typically just before battlefield use. The majority of stockpiled chemical weapons are unitary, already toxic in their existing state, and most are stored in one-ton bulk containers.

  Not every toxic chemical is a chemical weapon under international law. Agent Orange, the herbicide widely used by United States forces in the Vietnam War of 1955-1975, falls outside the OPCW definition because it was deployed for its herbicidal properties. White phosphorus, used as an incendiary, is similarly excluded. The weapon is not the chemical alone; it is the intent behind it.

• 3. From Antiquity to Industrial-Scale Gas

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  Simple chemical weapons appeared sporadically throughout antiquity and into the Industrial Age. It was not until the 19th century that the modern conception of chemical warfare took shape, as scientists and governments began proposing the deliberate use of asphyxiating or poisonous gases. Nations were alarmed enough that multiple international treaties followed, the first in 1899 under the Hague Convention, which prohibited employing poison and poisoned arms.

  World War I shattered those prohibitions. Chlorine gas and the choking agent phosgene were introduced to break the stalemate of trench warfare, and mustard gas followed. Most major powers employed these weapons. Military gas casualties across the war have been estimated in a range of 500,000 to 1.3 million, with additional civilian casualties from production accidents and collateral exposure. In most cases the gases did not kill outright; they blinded, scarred lungs, and disfigured those who survived.

  The interwar years brought occasional use by European colonial forces suppressing rebellions. Italy used poison gas during its 1936 invasion of Ethiopia. Meanwhile, Nazi Germany poured research into new chemical agents, discovering an entirely new class: nerve agents. The strategic decision not to deploy them against Allied forces appears to have rested on fear of retaliation rather than restraint. Allied planners had made comprehensive preparations for defensive and retaliatory chemical use and had stockpiled large quantities. Japan faced the same calculation differently, using chemical weapons against Chinese Kuomintang and communist troops, but avoiding deployment against Western powers for the same reason.

• 4. The Holocaust and Zyklon B

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  Nazi Germany's use of chemical agents against civilians stands apart from every other chapter in this history. Zyklon B, a commercial hydrogen cyanide product originally sold as a pesticide, was repurposed as the killing agent in the gas chambers of Nazi extermination camps. Carbon monoxide was also used extensively. The overwhelming majority of some three million deaths resulted from this poison gas program.

  This remains the deadliest use of poison gas in recorded history, and the Holocaust produced the largest death toll attributable to chemical weapons of any single conflict or campaign.

  The scale separates these killings from battlefield chemical warfare in every meaningful way. They were not aimed at enemy combatants; they were industrialized, systematic, and conducted against civilians, primarily Jews, in facilities built specifically for that purpose. The choice of Zyklon B was driven partly by its commercial availability and partly by a calculated effort to conceal the nature of what was happening from those being killed.

• 5. Cold War Stockpiles and Persistent Use

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  After World War II, Allied forces occupying Germany found large stockpiles of chemical weapons with no clear plan for disposal. Their solution was the sea. Into the Bornholm Basin they dumped 32,000 tonnes of chemical munitions. Another 2,000 tonnes went into the Gotland Basin. Most were packed in simple wooden crates, which accelerated the spread of the chemicals. Similar dumping occurred off European, Japanese, Russian, and United States coasts throughout the 20th century. Chemical agents and their breakdown products have since been detected in ocean sediment near historical dumping sites, and the long-term consequences remain unknown.

  Ashore, the Cold War became a race to accumulate. The Soviet and United States chemical weapons programs grew into the first and second largest in world history, focused on sarin, VX/VR, and mustard gas, intended primarily for battlefield use in Europe.

  In 1985, the United States Congress passed legislation requiring disposal of a stockpile exceeding three million chemical weapons, totaling 31,000 tons. Between 1982 and 1992, the Army reported approximately 1,500 leaking chemical weapons munitions. A 100-gallon mustard agent spill was reported at the Tooele Army Depot in Utah in 1993. Construction of the Johnston Atoll Chemical Agent Disposal System began in 1985 as the first full-scale prototype for the incineration baseline system. The program reached 45% destruction by June 2007 and completed elimination of all declared US chemical weapons on the 7th of July, 2023.

  The decades after the Cold War saw continued use in regional conflicts. Iraq deployed mustard gas and nerve agents against its own civilian population in the 1988 Halabja chemical attack. Syria used sarin, chlorine, and mustard gas in its civil war. Terrorist groups have also turned to these agents; the Tokyo subway sarin attack and the Matsumoto incident are the most documented cases.

• 6. The Treaty Architecture

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  International law has tried to constrain chemical weapons since the Hague Convention of 1899. That document's Article 23 prohibited poison and poisoned arms. A companion declaration barred projectiles designed to diffuse asphyxiating gases between signatory powers.

  The Washington Naval Treaty, signed on the 6th of February, 1922, attempted an outright ban on chemical warfare, but France rejected it, and the effort collapsed. The Geneva Protocol, signed on the 17th of June, 1925, and entering force on the 8th of February, 1928, went further, prohibiting use of both chemical and biological weapons in international armed conflict. Ukraine, the newest signatory, acceded on the 7th of August, 2003, bringing total state parties to 133. The protocol's weakness was its silence on production, storage, and transfer. Nations could stockpile freely while promising not to fire.

  The 1993 Chemical Weapons Convention addressed those gaps directly. It outlaws production, stockpiling, and use, and created the OPCW, based in The Hague, as the enforcing body. The OPCW has conducted 6,327 inspections at 235 chemical weapon-related sites and 2,255 industrial sites in 86 states parties since April 1997. Some 66,368 of 72,525 metric tonnes of declared stockpiles have been verified as destroyed. The treaty now counts 193 state parties.

  Syria and Russia are widely believed to have violated the convention's prohibitions on stockpiling and use. Israel and North Korea remain non-parties.