The U.S.-led invasion of Iraq began on March 20, 2003, after Congress authorized the use of force in October 2002 by votes of 77-23 in the Senate and 296-133 in the House.
The Iraq Survey Group's 2004 Duelfer Report concluded that Iraq did not possess stockpiles of weapons of mass destruction at the time of the invasion.
The Defense Casualty Analysis System records 4,431 U.S. military deaths and more than 31,000 wounded in Operation Iraqi Freedom between 2003 and 2011.
A 2013 Costs of War study at Brown University estimated direct U.S. budgetary costs of the Iraq War at roughly $1.7 trillion, with long-term veteran care raising projected totals higher.
Supporters cite the removal of Saddam Hussein, who was convicted by an Iraqi tribunal in 2006 for crimes against humanity; critics cite the rise of ISIS in Iraq and Syria beginning in 2013.