The Iraq Survey Group (ISG) was a fact-finding mission sent by the multinational force in Iraq to find the weapons of mass destruction alleged to be possessed by Iraq that had been the main ostensible reason for the invasion in 2003. Its final report, Comprehensive Report of the Special Advisor to the Director of Central Intelligence on Iraq WMD, was submitted to Congress and the president in 2004. It consisted of a 1,400-member international team organized by the Pentagon and Central Intelligence Agency to hunt for the alleged stockpiles of weapons of mass destruction, including chemical and biological agents, and any supporting research programs and infrastructure that could be used to develop WMD. The report acknowledged that only small stockpiles of chemical WMDs were found, the numbers being inadequate to pose a militarily significant threat.

Iraq actively researched and later employed weapons of mass destruction (WMD) from 1962 to 1991, when it destroyed its chemical weapons stockpile and halted its biological and nuclear weapon programs as required by the United Nations Security Council. The fifth president of Iraq, Saddam Hussein, was internationally condemned for his use of chemical weapons against Iranian and Kurdish civilians during the Iran–Iraq War in the 1980s. Saddam pursued an extensive biological weapons program and a nuclear weapons program, though no nuclear bomb was built. After the Gulf War, the United Nations located and destroyed large quantities of Iraqi chemical weapons and related equipment and materials; Iraq ceased its chemical, biological and nuclear programs.