WMD conjecture after the 2003 invasion of Iraq

The United Nations Monitoring, Verification and Inspection Commission (UNMOVIC) and the United States-led Iraq Survey Group (ISG) failed to find any of the alleged stockpiles of weapons of mass destruction in Iraq that were used as a rationale for the 2003 U.S.-led invasion. The United States effectively ended the search effort for unconventional weaponry in 2005, and the Iraq Intelligence Commission concluded that the judgements of the U.S. intelligence community regarding the continued existence of weapons of mass destruction and an associated military program were mistaken. The official findings of the CIA in 2004 were that Iraqi President Saddam Hussein "did not possess stockpiles of illicit weapons at the time of the U.S. invasion in March 2003 and had not begun any program to produce them."

During and immediately following these searches, many theories were proposed to explain the sudden disappearance of Iraqi WMD—assuming that any had, in fact, existed. These theories included conspiracy theories, accusations against other governments and claims of successful deception efforts by Saddam Hussein. In various theories, Russia, Syria, Lebanon, Iran, and Pakistan were all alleged to be involved with moving or concealing Iraq's supposed WMD arsenal. In 2004, a theory was advanced that WMD might still remain hidden somewhere within Iraq. While some remnant chemical warheads were discovered, dating to the Iran–Iraq War era, none were newer than 1991. Some of these chemical weapons were found near the Muthanna State Establishment facility northwest of Baghdad.

After much criticism of the war during the years that followed, every figure who had previously supported the claims of WMD in Iraq, with the exception of U.S. Vice President Dick Cheney, acknowledged that they had been wrong. A related debate also emerged over whether the figures who had pushed for war were inadvertently misled by intelligence or had, in fact, intentionally deceived the public.