Saddam Hussein was building up its chemical weapons arsenal with the help of a British firm, Margaret Thatcher’s government decided not to oppose it. In the 1980s Iraq, which was engaged in a brutal war against neighboring Iran, was seeking to boost its manufacture of chemical weapons. It succeeded, and numerous attacks resulted in estimated 50,000 Iranian deaths during the war and extra 50,000 deaths from prolonged effects of the weapons. In 1983, the British government learned about Saddam’s effort to produce mustard gas, but chose not to hamper it, partially because a British firm was involved. The company, Weir Pumps, supplied a number of pumps to an Indian contractor, which built a chemical plant in Iraqi Samarra. The plant was used to produce mustard gas. In 1985, the Thatcher government provided insurance guarantees to a British subsidiary of a German firm, which built a chemical plant in Fallujah. The UK government suspected that the plant would be used to produce mustard gas.
The Chemical Weapons Convention, which bans the production, stockpiling and use of chemical weapons and precursors, did not come into force until 1997. The Geneva Protocol of 1925 did ban the use of chemical weapons in international conflicts with possible reservation for responding to a chemical attack with chemical weapons.