Iraq War

The Iraq War began on 20 March 2003, when a coalition led by the United States and the United Kingdom—joined by Australia and Poland in the initial invasion—launched military operations against the Ba'athist government of Saddam Hussein. The stated rationale was that Iraq possessed weapons of mass destruction (WMD) and maintained ties to terrorism, claims advanced by the Bush administration and articulated by Secretary of State Colin Powell in his February 2003 presentation to the UN Security Council. No active WMD stockpiles were subsequently found, a conclusion confirmed by the Iraq Survey Group's Duelfer Report in 2004.

Baghdad fell on 9 April 2003, and Saddam Hussein was captured in December 2003, tried by an Iraqi tribunal, and executed in 2006. The Coalition Provisional Authority (CPA), led by L. Paul Bremer, governed Iraq until June 2004 and issued orders dissolving the Iraqi army and de-Ba'athifying the civil service—decisions widely criticized for fueling insurgency.

A complex multi-sided conflict followed, involving Sunni insurgents, Shi'a militias such as the Mahdi Army, and al-Qaeda in Iraq (later a precursor to ISIS). Sectarian violence peaked in 2006–2007, prompting the US "surge" of roughly 30,000 additional troops announced by President George W. Bush in January 2007.

The war's legal basis was contested: it proceeded without an explicit UN Security Council authorization, and UN Secretary-General Kofi Annan stated in 2004 that the invasion was, from the UN Charter's standpoint, "illegal." The UK's Chilcot Inquiry (Iraq Inquiry), published in 2016, concluded that military action was undertaken before peaceful options had been exhausted.

Under a 2008 Status of Forces Agreement signed by Bush and Prime Minister Nouri al-Maliki, US combat troops withdrew by 18 December 2011. Casualty estimates vary widely; Iraq Body Count documents over 100,000 violent civilian deaths during the period, while broader estimates run higher.