How did chemical warfare during World War I lead to later arms-control agreements?

The widespread use of chemical weapons during World War I—which resulted in over a million casualties—horrified the international community and created a moral imperative to prevent such atrocities from recurring. This reaction served as the primary catalyst for early arms control efforts.123

The first major milestone was the Geneva Gas Protocol of 1925, which banned the use of chemical and biological weapons in war. However, this protocol was limited; it did not prohibit the development, production, or stockpiling of these weapons, and many nations reserved the right to retaliate in kind.123

These inadequacies, combined with the continued threat of chemical warfare, eventually led to more comprehensive agreements. The Biological Weapons Convention (1972) addressed biological agents, and the Chemical Weapons Convention (1993) finally established a total ban on the development, production, and stockpiling of chemical weapons, supported by a robust verification regime administered by the Organisation for the Prohibition of Chemical Weapons.12