Battles & Wars › Modern conflicts › War on Terror
Iraq War
March 20, 2003 – December 2011· War· Middle East & Africa
Well documentedSolid records, physical evidence or scientific consensus.
A US-led coalition invaded Iraq in 2003 and toppled Saddam Hussein, then fought an insurgency and sectarian violence until leaving in 2011.
See it on the Battles & Wars map →What happened
The US and Britain argued Iraq hid weapons of mass destruction (WMD) and might aid terrorists; the UN Security Council did not explicitly authorize force. Baghdad fell April 9, 2003. Occupation authorities disbanded Iraq's army and purged Saddam's Baath Party, leaving many armed men jobless. Insurgency and Sunni–Shia killing peaked in 2006–07, until a US troop 'surge' and Sunni tribal alliances cut violence. No WMD stockpiles were found. About 4,500 US troops died; estimates of Iraqi deaths range from over 100,000 to more than 600,000.
Why it matters
It cost trillions of dollars, damaged US credibility when no WMD turned up, strengthened Iran's regional influence, and left the chaos in which the Islamic State grew.
How we know
The Iraq Survey Group's Duelfer Report (2004) on WMD, Britain's Chilcot Inquiry (2016), US military records, the Iraq Body Count database, and household mortality surveys published in The Lancet and PLOS Medicine.
Still debated
Whether leaders misled the public or were misled by bad intelligence is still argued, and Iraqi death estimates differ several-fold depending on method.
Connections (4)
▸Gulf War (Operation Desert Storm) set up the confrontation behind Iraq WarMostly agreed
The connection
The 1991 war freed Kuwait but left Saddam Hussein in power. Twelve years of UN sanctions, no-fly zones, weapons inspections and periodic US and British air strikes followed. Saddam's obstruction of inspectors fed suspicion that he still hid banned weapons, which became the main public case for the 2003 invasion.
When and how
Iraq and the UN, 1991–2003. Inspectors left in 1998 before US–British strikes; a 1998 US law made regime change official policy; UN Resolution 1441 (2002) gave Iraq a 'final opportunity'.
How sure are we?
UN Security Council resolutions, inspectors' reports, and US and British government documents that cite Iraq's post-1991 defiance as grounds for war.
Debates and open questions
Whether 2003 was the unfinished business of 1991 or a new choice driven by 9/11 and ideology is debated; some officials had sought Saddam's removal since the 1990s.
▸War on Terror was invoked to justify Iraq WarWell documented
The connection
After 9/11 the Bush administration argued that Saddam Hussein might hand weapons of mass destruction to terrorists, and claimed links to al-Qaeda. Framing Iraq as part of the war on terror helped win public and congressional support in 2002. Investigations later found no operational ties and no active weapons stockpiles.
When and how
Washington, 2002–03: Bush's 'axis of evil' speech (January 2002), Congress's October 2002 war authorization, and Colin Powell's UN presentation in February 2003.
How we know
The 9/11 Commission found no evidence of a collaborative operational relationship between Iraq and al-Qaeda; the Duelfer Report and Senate Intelligence Committee reviews (2004, 2008) found the WMD case was wrong.
Debates and open questions
Whether officials sincerely believed the threat or stretched thin intelligence remains debated; many historians argue 9/11 lowered the risk Washington would tolerate.
▸Iraq War created conditions for the rise of Islamic State (ISIS) territorial 'caliphate'Mostly agreed
The connection
Disbanding Iraq's army and purging Baath officials left many Sunni Arabs jobless and angry. Al-Qaeda in Iraq, founded by Abu Musab al-Zarqawi in 2004, fed on that anger. Nearly beaten by 2010, it revived under Abu Bakr al-Baghdadi after US troops left and Iraq's Shia-led government alienated Sunnis. Many ISIS commanders were former Iraqi officers.
When and how
Iraq, 2003–2014. Many future leaders met in the US-run prison Camp Bucca; the group seized Mosul in June 2014 as Iraqi troops fled.
How sure are we?
Captured ISIS documents, studies of its leadership showing many ex-Baathist officers, and US officials' own later judgments, including President Obama's in 2015.
Debates and open questions
How much blame lies with the 2003 invasion, the 2011 US withdrawal, Iraqi government sectarianism or Syria's war is debated; most analysts think all played a part.
▸Tomahawk cruise missile struck Baghdad at the start of the Iraq WarWell documented
The connection
The 2003 invasion began on March 20 with Tomahawks and stealth-jet bombs aimed at a Baghdad compound where Saddam Hussein was thought to be. 'Shock and awe' strikes on government buildings followed. About 800 Tomahawks were fired in the war's first weeks.
When and how
Baghdad, March 20–21, 2003, onward; launched from US and British ships and submarines in the Persian Gulf and Red Sea.
How we know
Pentagon briefings, Navy records and imagery of struck government buildings document the launches and targets.
Debates and open questions
Whether Saddam was at the Dora Farms compound at all remains unclear; 'shock and awe' did not, as some hoped, make the regime collapse by itself.