The Iraq War was justified by Saddam Hussein's possession of weapons of mass destruction.
The Iraq Survey Group's final report (September 2004) concluded Iraq had no active WMD programs and had dismantled them in 1991. The intelligence failure was compounded by political pressure to find a WMD case.
What changed?
When the Iraq Survey Group published its final report on September 30, 2004, it was the largest and most expensive weapons inspection effort in history, and its conclusion was unambiguous: Iraq had no weapons of mass destruction and had not had any since 1991. The 960-page Duelfer Report documented the systematic dismantlement of Iraqi weapons programs following the first Gulf War, the ongoing UN inspections of the 1990s, and the absence of any resumption of those programs in the years leading to the 2003 invasion.
The report received substantial coverage at the time. It was also released six weeks before a presidential election, during which the incumbent administration had strong incentives to contest, minimize, or reframe its findings. Administration officials argued that Saddam Hussein had retained the intent to reconstitute weapons programs once sanctions were lifted, which was technically true and entirely different from possessing weapons. The distinction between intent and capability collapsed in the political discourse.
For students in American high schools in fall 2004, the report's findings landed in a context where the war had already become a partisan symbol. Accepting the ISG's conclusions required accepting that the stated rationale for the war had been wrong, which many supporters of the invasion were not prepared to do, and which critics of the invasion took as confirmation of what they had argued. The epistemological problem, how do you change your mind when new evidence arrives, and what obligations follow?, was not typically what social studies classes addressed.
Subsequent investigations confirmed and extended the ISG's findings. The Senate Intelligence Committee found that the intelligence community had "overstated" the case and that there had been significant pressure to produce conclusions consistent with what policymakers wanted. Bob Woodward and other journalists documented the process by which uncertainty had been converted into confidence before the invasion.
The war killed an estimated 150,000 to 600,000 Iraqis, depending on the methodology, and approximately 4,500 American service members. Its cost exceeded $2 trillion. It destabilized Iraq in ways that contributed to the rise of ISIS. All of this followed from intelligence assessments that were wrong, presented as certainties they were not.
