Yesterday, President Trump announced that the United States is preparing to complete its military withdrawal from Iraq by the end of September 2026, which will bring to a close one of the longest overseas military deployments in American history. The withdrawal will end a twenty-three-year military presence that began with the U.S.-led invasion of Iraq in March 2003.

The announcement, made jointly by U.S. and Iraqi leaders, marks the conclusion of a mission that evolved dramatically over more than two decades. From overthrowing Saddam Hussein to counterinsurgency operations, to combating the Islamic State of Iraq and Syria, and most recently advising and supporting Iraqi security forces.

The American invasion of Iraq in 2003 changed the trajectory of the post-9/11 era for the United States and the Middle East. Following the terrorist attacks of September 11, 2001, the American military retaliated against Al-Qaeda in Afghanistan, because that group had planned and carried out the attacks against New York and Washington. But the invasion of Iraq quickly became the central front in the war on terrorism, even though terrorist groups like Al Qaeda never operated in Iraq until after the U.S. invaded in 2003.

Saddam Hussein, the former dictator of Iraq eventually captured and executed by American forces, was a brutal tyrant but he was also a secular ruler, and he was in fact an enemy of religiously inspired terrorist groups like Al-Qaeda. Iraq had nothing to do with 9/11, and despite voluminous evidence to prove that, the Bush Administration continued to insist the invasion of Iraq was necessary for U.S. national security.

Initially the Iraqi people welcomed the toppling of the regime of Saddam Hussein, but it quickly became apparent the Bush Administration had no plan for what to do next. With no plan to govern Iraq after Hussein’s removal, the Iraqi government collapsed and ordinary life became even more difficult for Iraqis. The Iraqi people’s initial enthusiasm for the U.S. invasion faded, and by 2004 an insurgency had begun to carry out attacks against U.S. forces in Iraq.

L. Paul Bremmer, the top U.S. official in Iraq after the invasion, disbanded the Iraqi military throwing thousands of well-trained soldiers out of work. From their ranks the anti-U.S. insurgency was born, but it rapidly grew and attracted jihadists from all over the world who wanted to come to Iraq to fight the U.S. military. Syrian dictator Asad facilitated the arrival of those jihadists to Iraq, often sending them by the busload over the Iraqi Syrian border.

The goal for the terrorist groups fighting in Iraq was maximum carnage, and they did not care how many Iraqis they killed in their onslaught against the U.S. military. Most of the Iraqi civilians killed in the next decade were killed by terrorist organizations or by sectarian groups seeking revenge against old enemies in Iraq. Without the iron rule of Saddam Hussein to keep warring groups in check in Iraq, old ethnic rivalries between Iraqi Sunni and Shia soon became bloody and so numerous they amounted to a de facto Iraqi civil war.

The U.S. military was unable to stop Iraqi on Iraqi violence, and Iraq’s broken government was in no position to do so either. Though American forces had strict rules of engagement in place forbidding the targeting of civilians, it became difficult for the U.S. military to distinguish civilians from terrorists, because jihadists often hid among the general population. In the decade following the 2003 invasion, terrorist attacks, sectarian violence, and U.S. military operations collectively killed tens of thousands of Iraqis and forced many more to flee their homes.

The rise of the Islamic State of Syria and Iraq, an even more violent and extreme terrorist group than Al Qaeda, was a direct result of the U.S. invasion of Iraq and subsequent failure to govern Iraq effectively. 

Iraq’s future remains uncertain, and the U.S. war with neighboring Iran is likely being closely watched by Iraqis. The U.S. withdrawal from Iraq will bring to a close a long chapter in American and Iraqi history, one whose lessons will likely be debated for decades to come.