Iraq actively researched weapons of mass destruction (WMD) and used chemical weapons from 1962 to 1991, after which its chemical weapons stockpile was destroyed its nuclear and biological weapon programs halted, in accordance with the United Nations Security Council's Resolution 687. The Iraqi government Saddam Hussein was internationally condemned for its chemical attacks against Iranian and Iraqi Kurdish civilians and troops during the Iran–Iraq War. Saddam pursued extensive biological and nuclear weapons programs, but did not construct a nuclear weapon. After the Gulf War, the United Nations Special Commission located, confiscated, and destroyed large quantities of Iraqi chemical weapons and infrastructure; Iraq ceased its chemical, biological and nuclear programs.
During the Iran–Iraq War, known Iraqi chemical weapons attacks between 1983 and 1988 were estimated to have caused 50,000 immediate casualties to Iranian troops. Civilians were also targeted; between 3,200 and 5,000 people were killed in the Halabja massacre. The attacks were led by Ali Hassan al-Majid, using mustard gas and nerve agents. In the Gulf War, US bombing and post-war demolition of Iraqi chemical weapons facilities were concluded to be the primary cause of Gulf War syndrome, experienced by over 40% of US veterans.