US troops have left Iraq, ending more than two decades of American military presence that began with the 2003 invasion.
Estimates of Iraqi deaths linked to the invasion and subsequent violence vary widely, with studies putting the toll from more than 200,000 to over 600,000.
The US returned to Iraq in 2014 to fight ISIS, and its military mission has now ended as Baghdad assumes greater responsibility for security.
The United States has withdrawn its remaining troops from Iraq, more than two decades after the 2003 invasion that toppled Saddam Hussein. US forces left the country on September 30, bringing to an end the latest phase of an American military presence that was interrupted in 2011 and resumed three years later to fight Islamic State.
The withdrawal was carried out under a 2024 agreement between Washington and Baghdad. Associated Press reported that it marked the end of the US-led coalition’s 12-year military mission against Islamic State. The US will continue to provide security support to Iraq, including training and intelligence assistance, but American troops are no longer stationed there.
2003: The invasion
The US-led invasion began in March 2003 under President George W Bush. His administration argued that Saddam Hussein’s government possessed weapons of mass destruction and posed a security threat. No stockpiles of such weapons were found after the invasion.
US forces rapidly overthrew Saddam’s government, but the conflict continued. An insurgency developed, attacks on American troops increased and sectarian violence spread.
Al Jazeera reported that the US military presence reached more than 170,000 troops at the height of the occupation in 2007.
Iraqi deaths: Why the toll varies
There is no single agreed figure for the number of Iraqis who died as a result of the 2003 invasion and the violence that followed. Estimates vary widely depending on whether researchers count only documented violent deaths or also deaths indirectly linked to the war.
Al Jazeera’s review of casualty estimates found a wide gap between studies. The Lancet estimated about 601,000 violent deaths between the invasion and June 2006, while the Iraq Index put the number of civilian deaths at nearly 115,000 from March 2003 to April 2011. The difference reflects the methods used to count deaths and the difficulty of establishing a complete record during years of conflict.
Reuters has reported that more than 200,000 Iraqi civilians were killed in war-related violence following the invasion, while noting that the overall toll remains disputed.
4,419 US military deaths
The figure of 4,419 US military deaths refers to Operation Iraqi Freedom. AP has reported that 4,419 US troops died during the operation, including combat and non-combat deaths.
$1.79 trillion in costs
Reuters reported that the Costs of War project at Brown University estimated the US cost of the wars in Iraq and Syria at $1.79 trillion through early 2023. The estimate includes Pentagon and State Department spending, veterans’ care and interest on debt financing the conflicts.
The $1.79 trillion figure should therefore be described as the estimated US cost of the Iraq and Syria wars, rather than the cost of Iraq alone.
2011: First withdrawal
In December 2011, the United States withdrew its remaining combat forces from Iraq under an agreement with Baghdad. Political and sectarian instability continued, and by 2014 Islamic State had captured Mosul and large parts of northern and western Iraq, prompting Baghdad to seek international military assistance.
2014: US troops return
The United States began returning forces to Iraq in 2014 at the Iraqi government’s invitation as part of the international campaign against Islamic State.
Washington was no longer seeking to remove Iraq’s government or occupy the country. Instead, US and coalition forces supported Iraqi and Kurdish forces fighting Islamic State through air power, intelligence, training and logistical assistance.
The US had maintained about 2,500 troops during the later phase of the mission, before the final contingent was reduced to a few hundred. Al Jazeera reported that the force was largely in advisory and support roles.
AP reported that coalition combat operations against Islamic State in Iraq ended in 2021, although US troops remained to train and support Iraqi forces.
2024-2026: The final exit
Washington and Baghdad agreed in 2024 to wind down the coalition mission in stages. Combat operations inside Iraq were due to end first, followed by the withdrawal of the remaining coalition forces.
The final deadline was September 30, 2026. By then, US forces had already left bases in most parts of Iraq, with the remaining contingent concentrated in the Kurdistan Region.
AP reported that the final American troops departed a base in northern Iraq, completing the withdrawal. The Pentagon described the departure as an orderly conclusion to the 12-year campaign against Islamic State.
The withdrawal ends the US-led coalition’s military mission in Iraq, but not the wider relationship between Washington and Baghdad. Al Jazeera reported that the two sides are moving towards bilateral security cooperation involving areas such as training, military assistance and liaison arrangements.
What changes for Iraq?
The most immediate change is that Iraqi forces will have to manage without several capabilities previously supplied by the US.
Al Jazeera reported that US air-defence systems are being withdrawn, while Kurdish officials have warned of possible losses in US intelligence, logistical support and drones. The concern is particularly acute in the Kurdistan Region, where US air-defence systems have helped protect against missiles and drones.
Iraq says it has already taken over many responsibilities. Its military has increasingly conducted its own reconnaissance using drones. Air defence remains the more difficult gap, with Baghdad seeking systems from countries including South Korea, Türkiye and the United States.
Islamic State is another concern. The group no longer controls the territory it seized in 2014 and is far weaker than it was at its peak, but its cells remain active in Iraq.
Reuters reported that Iraqi security officials had detected increased Islamic State activity ahead of the US departure. Iraqi officials and analysts have warned that reduced access to US intelligence and other capabilities could create security gaps that Islamic State cells might exploit.
Reuters reported that Iran and its allied Iraqi armed groups have portrayed the US departure as a strategic victory, while analysts have warned that Iran-backed groups could gain greater room to shape Iraq’s security and political decisions.
Baghdad is also trying to bring armed groups under state control. AP reported that the government has pushed back its deadline for bringing powerful Iran-aligned factions under state control to June 2027 after some groups resisted earlier demands.
The US military mission in Iraq is over, but the US-Iraq security relationship continues. For Baghdad, the immediate challenge is closing capability gaps, containing Islamic State cells and managing Iran-backed armed groups without the American military presence that has shaped Iraqi security for much of the past two decades.
