| 1874 | The Brussels Convention on the Law and Customs of War | Prohibits the employment of poison or poisoned weapons, and the use of arms, projectiles or material to cause unnecessary suffering |
| 1899/1907 | Hague Peace Conferences | Bans on use of poisoned weapons, asphyxiating, or deleterious gases |
| 1925 | Geneva Protocol | Ban on chemical weapons use, but no prohibition on development – 132 parties by 2000; Japan did not become a signatory until 1970 |
| 1972 | Biological and Toxin Weapons Convention | Comprehensive biological weapons prohibition, but no verification mechanism – 143 parties and 17 signatories by 2000 |
| 1993 | Chemical Weapons Convention | Comprehensive bans on development, production, stockpiling and use of chemical weapons, with destruction timelines; Preparatory Commission for OPCW established |
| 1997 | OPCW, The Hague | The Chemical Weapons Convention enters into force for 87 state parties; The OPCW commences its operations in The Hague; Inspection begins |
