The Iraq War: 2003–2011, and the long shadow after it

By Khalid Al-Harbi

On 20 March 2003, a United States-led coalition invaded Iraq. Three weeks later, American tanks were in Baghdad and the statue of Saddam Hussein was being pulled down in Firdos Square. The war that was supposed to be short became one of the defining catastrophes of the twenty-first century: an occupation that dissolved the Iraqi state, an insurgency that hardened into sectarian civil war, a detention scandal that stained the invaders’ cause, a surge that reduced the killing without resolving its causes, and a withdrawal that left a fragile state facing the rise of the Islamic State. This is the story of how a war of choice remade Iraq, the Middle East, and the credibility of American power.

Origins: 9/11, Iraq, and the road to a war of choice

The Iraq War cannot be understood without the attacks of 11 September 2001. Nineteen hijackers, directed by the al-Qaeda network based in Afghanistan, killed nearly 3,000 people in New York, at the Pentagon, and in Pennsylvania. The United States responded first in Afghanistan, toppling the Taliban regime that had sheltered al-Qaeda. But within the administration of President George W. Bush, a second target was already under discussion: Iraq, ruled since 1979 by Saddam Hussein.

Saddam Hussein was no stranger to American power. Iraq had fought a devastating eight-year war with Iran in the 1980s, during which the United States had tilted toward Baghdad. In 1990, Iraq invaded Kuwait, and a U.S.-led coalition expelled it in the Gulf War of 1991. After that war, the United Nations imposed sweeping sanctions and a weapons-inspection regime. Iraq was required to destroy its chemical, biological, and nuclear weapons programmes and to submit to verification. Through the 1990s, inspectors from the United Nations Special Commission (UNSCOM) destroyed large quantities of Iraqi weaponry, but Saddam’s pattern of obstruction, concealment, and periodic expulsion of inspectors left deep uncertainty about what remained. In 1998, inspectors left Iraq amid a crisis, and the United States and Britain bombed Iraqi sites in Operation Desert Fox. For the next four years, there were no inspectors on the ground.

After 9/11, the Bush administration adopted a doctrine of pre-emption: the United States would act against gathering threats before they fully formed, rather than waiting to be attacked. In his State of the Union address of January 2002, President Bush described Iraq, Iran, and North Korea as an “axis of evil.” Senior officials argued that Saddam Hussein, who had used chemical weapons against Iranian troops and against Iraqi Kurds at Halabja in 1988, could not be allowed to possess weapons of mass destruction in a post-9/11 world — and that he might one day hand such weapons to terrorists. Critics would later note that no evidence ever established an operational link between Saddam’s secular Baathist regime and al-Qaeda, whose ideology he had long suppressed. But in the atmosphere after 9/11, the claim that the two threats might converge proved politically powerful.

Through 2002, the administration built its public case. In October 2002, the United States Congress authorised the use of military force against Iraq. In November 2002, the UN Security Council unanimously adopted Resolution 1441, giving Iraq a “final opportunity” to disarm and readmitting inspectors under the UN Monitoring, Verification and Inspection Commission (UNMOVIC), led by Hans Blix, and the International Atomic Energy Agency (IAEA), led by Mohamed ElBaradei. Inspectors returned and searched hundreds of sites. They found no stockpiles of weapons of mass destruction, though they reported unresolved questions and Iraqi obstruction on some points. The IAEA concluded that Iraq had not revived its nuclear weapons programme. The intelligence picture, however, was being presented in Washington and London in far more certain terms than the inspectors’ cautious findings supported.

The most famous set-piece came on 5 February 2003, when U.S. Secretary of State Colin Powell addressed the UN Security Council and presented what he called evidence of Iraq’s mobile biological weapons laboratories, its concealment of chemical weapons, and its pursuit of nuclear weapons, including aluminium tubes supposedly intended for uranium enrichment. Powell’s presentation — delivered by the administration’s most credible figure — persuaded many wavering observers. It would later be shown to rest on sources that were wrong, exaggerated, or fabricated, including the testimony of an Iraqi defector codenamed “Curveball,” whose claims about mobile bioweapons labs were subsequently discredited. Powell himself would later call the speech a blot on his record. The British government’s own dossiers, including the September 2002 dossier that claimed Iraq could deploy chemical or biological weapons within 45 minutes, were similarly discredited by the later Iraq Inquiry.

Diplomacy failed. France, Germany, Russia, and China opposed a second Security Council resolution explicitly authorising force, and the United States and Britain concluded that they would proceed without one, assembling a “coalition of the willing” whose major military contributors were the United States and Britain, with smaller contingents from Australia, Poland, and others. On 17 March 2003, President Bush gave Saddam Hussein and his sons 48 hours to leave Iraq. They did not. On 20 March 2003 (19 March in Washington), the invasion began with air strikes on a compound near Baghdad where Saddam was believed to be, followed by a ground invasion from Kuwait.

The invasion: shock and awe, then a statue falls

The invasion force, built around the U.S. Army’s 3rd Infantry Division, the 1st Marine Division, and British forces in the south, numbered roughly 150,000 American troops and some 45,000 British troops, with smaller allied contingents. The campaign opened with a bombardment campaign dubbed “shock and awe,” intended to paralyse Iraqi command and control. American and British forces advanced rapidly up the Tigris and Euphrates valleys, bypassing some resistance, fighting sharp battles at Nasiriyah, Najaf, and elsewhere, and seizing airfields and oil infrastructure. Iraqi resistance was disorganised; many units melted away rather than fighting for a regime that had hollowed out its own army through fear, patronage, and sanctions.

On 9 April 2003, U.S. forces entered Baghdad. In Firdos Square, Iraqis and American Marines pulled down a giant statue of Saddam Hussein, an image broadcast around the world as the symbol of liberation. The regime collapsed with startling speed. Saddam fled, was captured by U.S. forces in December 2003 hiding in a pit near Tikrit, and was later tried by an Iraqi court, convicted of crimes against humanity for the 1982 massacre at Dujail, and executed on 30 December 2006. On 1 May 2003, President Bush landed on the aircraft carrier USS Abraham Lincoln and declared, beneath a banner reading “Mission Accomplished,” that major combat operations in Iraq had ended. The banner would become one of the most mocked symbols of premature triumphalism in modern American history, because the hardest part of the war had not yet begun.

In the weeks after the fall of Baghdad, Iraq descended into looting and disorder. The National Museum in Baghdad was ransacked, ministries were stripped, and arms depots were left unguarded — weapons that would later arm the insurgency. The invading force, configured for a fast conventional campaign, had too few troops to secure a country of some 25 million people. The failure to impose order in those first weeks is widely regarded by historians as the original sin of the occupation: it signalled to Iraqis that the new authority could not protect them, and it allowed the infrastructure of resistance to take root.

The occupation: de-Baathification and the dissolution of the army

The United States established the Coalition Provisional Authority (CPA) under L. Paul Bremer to govern Iraq until a new Iraqi government could be formed. Two CPA orders, issued in May 2003, would shape everything that followed. Order No. 1, on 16 May 2003, instituted sweeping de-Baathification, barring senior members of Saddam’s Baath Party from public employment. In a state where party membership had been a condition of professional advancement for teachers, doctors, engineers, and civil servants, the order gutted the bureaucracy. Order No. 2, on 23 May 2003, dissolved the Iraqi army, the security services, and the Ministry of Defence, putting some 400,000 armed men out of work, many with their weapons, and stripping the state of its coercive spine.

Defenders of the orders argued that the Baathist army was an instrument of Saddam’s terror and could not be the foundation of a new Iraq. Critics, including many American military officers and later historians, argue that the two orders together created a vast pool of humiliated, unemployed, armed Sunni men with every incentive to resist, while simultaneously destroying the institutions that might have held Iraq together. The debate continues, but the sequence is clear: the occupation dismantled the Iraqi state faster than it built a replacement, and the vacuum was filled by militias, tribal networks, religious parties, and foreign fighters.

The CPA also pursued an ambitious economic agenda, including rapid privatisation and the opening of Iraq to foreign investment, which many Iraqis experienced as distant from the urgent realities of electricity, water, fuel, and security. Meanwhile, a new Governing Council was appointed in July 2003, drawn largely from exiled opposition figures and Kurdish and Shia leaders, which many Sunni Iraqis saw as unrepresentative. The United Nations, whose Baghdad headquarters was bombed in August 2003, killing the UN envoy Sergio Vieira de Mello and 21 others, pulled back from Iraq, further narrowing the occupation’s international legitimacy.

Insurgency, Abu Ghraib, and the road to civil war

By the summer of 2003, a Sunni-led insurgency was gathering force in the so-called Sunni Triangle west and north of Baghdad, in Fallujah, Ramadi, Tikrit, and Samarra. Former Baathists, army officers, nationalists, and Islamists — including foreign fighters drawn by the cause of resisting the American occupation — attacked coalition patrols, Iraqi police recruits, and collaborators. In August 2003, insurgents bombed the Jordanian embassy and the UN headquarters in Baghdad. In November 2003, they shot down an American Chinook helicopter, killing 16 soldiers. The insurgency’s most brutal face was Abu Musab al-Zarqawi’s network, which would later become al-Qaeda in Iraq. Zarqawi pioneered suicide bombings against Shia civilians and religious sites, deliberately seeking to ignite sectarian war.

In April 2004, the United States fought two battles simultaneously: a Shia uprising led by the cleric Muqtada al-Sadr’s Mahdi Army, and a Sunni uprising in Fallujah after the killing and mutilation of four American contractors there. The First Battle of Fallujah ended in a negotiated withdrawal; the Second Battle of Fallujah, in November 2004, was one of the bloodiest urban battles American forces had fought since Vietnam, leaving much of the city destroyed. That same spring, the world learned of Abu Ghraib. Photographs published in April 2004 showed American military police abusing detainees at Abu Ghraib prison: prisoners hooded, leashed, piled naked, threatened with dogs, and subjected to sexual humiliation. The images, and the later investigations, showed abuses that went beyond a few “bad apples” and reflected failures of command, training, and interrogation policy. Abu Ghraib became a recruiting tool for the insurgency and a permanent wound to the American claim to be liberating Iraq.

On 28 June 2004, sovereignty was formally transferred to an interim Iraqi government led by Iyad Allawi, though the reality of American power did not change. Elections in January 2005, boycotted by many Sunnis, produced a Shia-led government. A referendum in October 2005 approved a new constitution, and parliamentary elections in December 2005 confirmed Shia and Kurdish dominance. But the political settlement excluded too many Sunnis, and the security situation was deteriorating fast. On 22 February 2006, the bombing of the golden-domed al-Askari Shrine in Samarra, one of Shia Islam’s holiest sites, detonated the sectarian civil war. Shia militias, some operating from within the Interior Ministry, carried out death-squad killings of Sunnis; Sunni insurgents answered with car bombs against Shia markets, mosques, and pilgrims. Baghdad was carved into sectarian enclaves by walls, checkpoints, and ethnic cleansing. By late 2006, Iraq was losing an estimated 2,000 to 3,000 civilians a month to sectarian murder, and the American project in Iraq appeared to be failing.

The surge: less killing, unresolved politics

In January 2007, President Bush announced a “surge” of more than 20,000 additional American troops, bringing U.S. forces in Iraq to over 160,000, under the command of General David Petraeus, with a new counterinsurgency doctrine emphasising the protection of the population rather than the pursuit of the enemy. American forces moved into Baghdad neighbourhoods, established joint security stations with Iraqi forces, and sought to separate sectarian killers from civilians. Simultaneously, the “Anbar Awakening” saw Sunni tribal leaders in Anbar province turn against al-Qaeda in Iraq, which had overreached through brutality, extortion, and the imposition of its harsh rule. The United States funded and armed these Sunni “Sons of Iraq,” tens of thousands of former insurgents who turned to fighting al-Qaeda.

Violence fell dramatically. Monthly civilian deaths dropped from thousands to hundreds. Al-Qaeda in Iraq was pushed back, and Baghdad’s sectarian cleansing, grimly, had already largely separated communities, reducing the opportunities for murder. The surge is often credited with rescuing the American mission from defeat. But the political reconciliation that the surge was supposed to create space for never fully arrived. The Shia-led government of Prime Minister Nouri al-Maliki did not integrate the Sunni Sons of Iraq into the state at the scale promised, did not resolve the status of Kirkuk or the distribution of oil revenue, and increasingly centralised power. The underlying sectarian bargain remained broken. The surge bought time; it did not settle Iraq’s future.

In November 2008, Iraq and the United States signed a Status of Forces Agreement (SOFA) that required all American forces to withdraw by the end of 2011. President Barack Obama, who had opposed the invasion as a candidate, honoured that timetable. American combat troops left Iraqi cities in mid-2009, and the last U.S. convoy crossed into Kuwait on 18 December 2011. The war, as an American combat mission, was over.

Casualties and the human cost

The human cost of the Iraq War remains contested, and the range of estimates reflects both the chaos of the war and the politics of counting. The Iraq Body Count project, which compiles documented violent civilian deaths from press reports, morgues, and official records, has recorded more than 200,000 documented civilian deaths from violence in Iraq since 2003. Surveys using different methodologies, including the widely debated 2006 Lancet survey, produced far higher estimates. The Costs of War Project at Brown University has estimated that more than 300,000 people died directly from war-related violence in Iraq, including Iraqi civilians, security forces, insurgents, and coalition troops, with many more deaths attributable indirectly to the destruction of infrastructure, healthcare, and livelihoods. More than 4,400 American service members were killed in Iraq, and tens of thousands more were wounded, many with traumatic brain injuries and post-traumatic stress. British forces lost 179 personnel.

Beyond the dead, millions were displaced. At the height of the sectarian war, the United Nations High Commissioner for Refugees estimated that more than two million Iraqis had fled the country, mostly to Syria and Jordan, and more than two million more were internally displaced. Many never returned. Iraq’s professional class — doctors, professors, engineers — was decimated by murder, flight, and exile. The war’s financial cost to the United States is estimated by the Costs of War Project at more than two trillion dollars, with long-term obligations for veterans’ care adding hundreds of billions more. Iraq’s own economic losses, in destroyed infrastructure, lost oil revenue, and foregone development, are incalculable in any single figure.

Aftermath: ISIS and the war that did not end

The withdrawal of American forces did not end Iraq’s war. Prime Minister Maliki’s government, increasingly sectarian and authoritarian, marginalised Sunni politicians, arrested Sunni protesters, and hollowed out the army through corruption and patronage. Al-Qaeda in Iraq, which had been battered but not destroyed, regrouped in Syria amid that country’s civil war, rebranded itself as the Islamic State in Iraq and Syria (ISIS), and in June 2014 swept back into Iraq, capturing Mosul, Iraq’s second city, as Iraqi divisions collapsed and fled. ISIS declared a caliphate across Iraq and Syria, committed genocide against the Yazidi people, enslaved Yazidi women, and carried out mass executions of Shia soldiers, Christians, and others. The United States returned to Iraq with air power, advisers, and special forces to support a new Iraqi government and Kurdish forces in the fight against ISIS, a campaign that culminated in the recapture of Mosul in 2017 after nine months of devastating urban combat that left much of the old city in ruins.

Iraq today is a sovereign state with elections, a fractious parliament, and a degree of pluralism that did not exist under Saddam. It is also a state deeply penetrated by Iranian influence, by Shia militias mobilised against ISIS that became a permanent armed force, by Kurdish autonomy that stops short of independence, and by corruption that has repeatedly brought protesters into the streets. The American invasion removed a dictator who had murdered hundreds of thousands of his own people, but it also unleashed forces — sectarianism, jihadism, Iranian power, and Kurdish separatism — that its architects neither foresaw nor controlled. The war’s supporters argue that Iraqis are freer than they were under Saddam; its critics argue that the price, in lives, regional destabilisation, and American credibility, was catastrophically disproportionate to any gain.

Key figures

Saddam Hussein (1937–2006): President of Iraq from 1979 to 2003. Built a brutal police state, waged war on Iran, invaded Kuwait, used chemical weapons, and was toppled by the 2003 invasion. Captured in December 2003, tried by an Iraqi court, and executed in 2006.

George W. Bush (born 1946): President of the United States, 2001–2009. Ordered the invasion of Iraq on the basis of weapons-of-mass-destruction claims that proved false. Later acknowledged intelligence failures but defended the decision to remove Saddam.

Tony Blair (born 1953): Prime Minister of the United Kingdom, 1997–2007. Committed Britain as the invasion’s principal ally. The 2016 Iraq Inquiry (Chilcot Report) concluded that the invasion was not a last resort and that the intelligence case had been presented with a certainty that was not justified.

Colin Powell (1937–2021): U.S. Secretary of State, 2001–2005. Presented the administration’s case for war to the UN Security Council on 5 February 2003. Later called it a blot on his record.

L. Paul Bremer (born 1941): Head of the Coalition Provisional Authority, 2003–2004. Issued the de-Baathification and army-dissolution orders that are widely blamed for fuelling the insurgency.

Hans Blix (born 1928): Head of UNMOVIC, the UN weapons-inspection team. Reported that inspectors had found no weapons of mass destruction before the invasion, and criticised the rush to war.

Abu Musab al-Zarqawi (1966–2006): Jordanian militant who led al-Qaeda in Iraq. Pioneered sectarian suicide bombings against Shia civilians. Killed in a U.S. air strike in June 2006; his network later evolved into ISIS.

Muqtada al-Sadr (born 1974): Shia cleric who led the Mahdi Army uprising against the occupation in 2004 and remained a major, unpredictable force in Iraqi politics for two decades.

David Petraeus (born 1952): U.S. general who commanded the surge in 2007–2008 and oversaw the counterinsurgency strategy that reduced violence, later director of the CIA.

Nouri al-Maliki (born 1950): Prime Minister of Iraq, 2006–2014. Oversaw the reduction in violence after the surge but also the sectarian consolidation of power that preceded the ISIS takeover of Mosul.

Timeline

• 11 September 2001: Al-Qaeda attacks in the United States kill nearly 3,000 people; the Bush administration adopts a doctrine of pre-emption.
• 29 January 2002: President Bush’s State of the Union names Iraq in an “axis of evil.”
• 11 October 2002: U.S. Congress authorises military force against Iraq.
• 8 November 2002: UN Security Council Resolution 1441 gives Iraq a “final opportunity” to disarm.
• 5 February 2003: Secretary of State Colin Powell presents the U.S. case for war to the UN Security Council.
• 20 March 2003: U.S.-led coalition invades Iraq.
• 9 April 2003: U.S. forces enter Baghdad; Saddam’s statue falls in Firdos Square.
• 1 May 2003: President Bush declares major combat operations over under a “Mission Accomplished” banner.
• 16–23 May 2003: CPA Orders No. 1 and No. 2 impose de-Baathification and dissolve the Iraqi army.
• 19 August 2003: Bombing of UN headquarters in Baghdad kills envoy Sergio Vieira de Mello and 21 others.
• 13 December 2003: Saddam Hussein captured near Tikrit.
• April 2004: Abu Ghraib abuse photographs published; First Battle of Fallujah; al-Sadr uprising.
• 28 June 2004: Sovereignty transferred to interim Iraqi government.
• November 2004: Second Battle of Fallujah.
• 30 January 2005: First democratic elections in Iraq since 1958.
• 22 February 2006: Bombing of the al-Askari Shrine in Samarra ignites sectarian civil war.
• 7 June 2006: Zarqawi killed in U.S. air strike.
• 30 December 2006: Saddam Hussein executed.
• January 2007: President Bush announces the surge; General Petraeus takes command.
• November 2008: U.S.–Iraq Status of Forces Agreement sets end-2011 withdrawal deadline.
• 18 December 2011: Last U.S. troops leave Iraq.
• June 2014: ISIS captures Mosul; the war’s aftermath enters a new phase.
• July 2017: Mosul recaptured from ISIS after nine months of battle.

The legacy

Sources and further reading

• The Iraq Inquiry (Chilcot Report), Report of the Iraq Inquiry, United Kingdom, 2016 — the definitive British official inquiry into the decision to invade and the conduct of the war.
• U.S. Senate Select Committee on Intelligence, Report on the U.S. Intelligence Community’s Prewar Intelligence Assessments on Iraq, 2004 — official U.S. assessment of the intelligence failures.
• Iraq Survey Group, Comprehensive Report of the Special Advisor to the Director of Central Intelligence on Iraq’s Weapons of Mass Destruction (Duelfer Report), 2004 — concluded Iraq had no stockpiles of weapons of mass destruction at the time of the invasion.
• National Commission on Terrorist Attacks Upon the United States, The 9/11 Commission Report, 2004.
• UN Security Council Resolution 1441 (2002), text via the United Nations.
• Iraq Body Count, database of documented civilian deaths in Iraq, iraqbodycount.org.
• Costs of War Project, Brown University, estimates of deaths and U.S. costs of the Iraq War.
• Rajiv Chandrasekaran, Imperial Life in the Emerald City: Inside Iraq’s Green Zone (2006).
• Thomas E. Ricks, Fiasco: The American Military Adventure in Iraq (2006).
• Dexter Filkins, The Forever War (2008).
• Bob Woodward, State of Denial (2006).
• Encyclopaedia Britannica, “Iraq War” entry, and U.S. Department of Defense casualty releases.