Last US troops leave Iraq, ending 12-year anti-ISIS mission

The United States has completed the withdrawal of its remaining forces and military equipment from Iraq, formally ending the US-led Operation Inherent Resolve mission in the country and closing the latest chapter of an American military presence that began with the 2003 invasion and was renewed in 2014 to fight the Islamic State group.

US Central Command announced on Wednesday that American forces and equipment had completed their “orderly departure” from Erbil Air Base in Iraq's semi-autonomous Kurdish region on September 30. The withdrawal was carried out under a 2024 agreement between Washington and Baghdad to wind down the coalition's military mission against ISIS.

President Donald Trump welcomed the departure, portraying it as the conclusion of a costly period of American military involvement in Iraq. The withdrawal, however, does not mean the end of US-Iraq defence ties or Washington's wider counter-ISIS operations in the region.

Trump welcomes end of mission

Trump said the final withdrawal brought to an end what he described as a prolonged and costly American involvement in Iraq. He criticised the original decision to enter the country and said the withdrawal would close that chapter of US foreign policy.

The President's remarks came as the Pentagon formally declared the conclusion of Operation Inherent Resolve's mission inside Iraq. The US military said the withdrawal marked a transition from a wartime coalition operation to an Iraqi-led security effort supported through a more conventional bilateral defence relationship.

The departure had been planned well before Wednesday. Washington and Baghdad reached an agreement in September 2024 setting out a phased end to the US-led coalition's military mission, with September 30, 2026 eventually established as the final date for the departure of coalition forces from Iraq.

The agreement was negotiated during the Biden administration and the final phase of the withdrawal has been implemented under Trump.

A military presence spanning 23 years

The departure carries particular historical significance because US forces first invaded Iraq in March 2003, overthrowing Saddam Hussein's government. At its peak in 2007, the American military deployment in Iraq exceeded 170,000 troops as the country was gripped by an insurgency and sectarian violence.

The United States formally withdrew its combat forces in December 2011. That departure, however, did not prove permanent.

American forces returned in 2014 at the invitation of the Iraqi government after ISIS captured Mosul and seized large parts of northern and western Iraq. Washington subsequently established Operation Inherent Resolve alongside an international coalition to support Iraqi and Kurdish forces fighting the militant group.

ISIS lost the last of its territorial control in Iraq in 2017, although remnants continued to operate through sleeper cells and small-scale attacks. Coalition combat operations in Iraq ended in 2021, but approximately 2,500 American troops remained for training, intelligence support and counter-terrorism operations.

Wednesday's withdrawal therefore ends the 12-year American military mission that began with the return of US forces in 2014, while also bringing to a close a broader period of direct US military presence in Iraq stretching back, with an interruption between 2011 and 2014, to the 2003 invasion.

Erbil was last major US position

The American military had already withdrawn from most of its remaining positions in Iraq before the September 30 deadline. Erbil Air Base in the Kurdish region became the final major location from which US forces and equipment had to be removed.

The base had assumed additional importance because of its location and the continuing US-led campaign against ISIS in neighbouring Syria. American air-defence systems stationed around Erbil had also provided protection against missile and drone attacks.

CENTCOM said the departure of forces from Erbil completed the Iraq component of Operation Inherent Resolve. The Combined Joint Task Force overseeing the operation remains active but has shifted its headquarters to Jordan.

American forces will also continue counter-ISIS operations in Syria alongside coalition partners and Syrian forces. The Iraq withdrawal, therefore, ends the coalition's military mission on Iraqi territory rather than Washington's entire military and counter-terrorism presence in the Middle East.

Iraq takes responsibility for ISIS threat

The Pentagon said Iraqi Security Forces, including the Peshmerga in the Kurdistan Region, would now assume primary responsibility for preventing ISIS remnants from rebuilding their networks.

Washington maintains that ISIS no longer poses the organised military threat it did a decade ago, when the group controlled large territories in Iraq and Syria and declared a self-styled caliphate. Small cells, however, remain active in parts of the region.

The United States intends to continue providing targeted training and intelligence assistance to Iraqi forces under the bilateral security relationship. That arrangement is different from maintaining American forces in Iraq as part of the international coalition mission.

For Baghdad, the withdrawal represents an important assertion of sovereignty. Iraqi authorities had repeatedly insisted that their security forces were capable of confronting ISIS without a permanent foreign military deployment.

Iran-backed militias pose another challenge

The American departure also changes Iraq's internal security equation. Several powerful Iran-aligned armed groups have long cited the US military presence as justification for maintaining weapons outside direct state control.

Iraqi Prime Minister Ali al-Zaidi had set September 30 as a deadline for non-state armed groups to surrender their weapons, arguing that the withdrawal of foreign troops removed one of the principal arguments used by militias to maintain independent arsenals.

Some smaller groups have moved towards complying with the government's demands, but several powerful Iran-aligned factions have resisted disarmament. Bringing weapons under exclusive state control is consequently expected to be one of Baghdad's most difficult security challenges after the American withdrawal.

The issue has acquired additional significance amid heightened tensions between Washington and Tehran. US military facilities in Iraq and elsewhere in the region have repeatedly been targeted during periods of confrontation involving Iran and allied armed groups.

New phase in US-Iraq relationship

Despite the troop withdrawal, Washington has stressed that it is not severing its security relationship with Baghdad. The Pentagon said the two countries would move towards a more conventional bilateral partnership covering training, intelligence and other areas of defence cooperation.

The United States is also expected to maintain diplomatic, commercial and intelligence engagement with Iraq. American forces stationed elsewhere in the Middle East will retain the ability to conduct counter-terrorism operations when required.

For Iraq, however, October 1 marks the beginning of a substantially different security arrangement. Iraqi forces will now carry primary responsibility for suppressing ISIS remnants, securing the country's borders and confronting armed groups operating outside state authority.

The departure from Erbil closes the operational headquarters of America's latest military mission inside Iraq. Whether Iraqi forces can prevent an ISIS resurgence while Baghdad attempts to bring powerful militias under state authority will shape the security consequences of the withdrawal long after the last American troops have left.