US Forces Leave Iraq After 20 Years: Iran Influence and ISIS Security Risks
US forces leave Iraq after more than two decades, raising questions over Iran’s influence, Iraqi security and the risk of an ISIS resurgence.
Raja Awais Ali
9/29/20264 min read
US Forces Leave Iraq After 20 Years: Iran Influence and ISIS Security Risks
The US is concluding the withdrawal of its forces from Iraq after more than two decades of military involvement, with the remaining personnel set to leave the country’s last bases by September 30, 2026. The departure marks the end of a long and costly US military presence which began with the 2003 invasion of Iraq as well as fighting Islamic State. While the withdrawal is seen as a victory by Iran and its allied groups, Iraqi security officials and local leaders have expressed concerns over the country’s ability to maintain the security environment without American military support. They also warn that Iran-backed armed groups may gain greater influence and that Islamic State could aim to exploit any security gap.
The US invasion of Iraq began in 2003 with the aim of toppling Saddam Hussein’s government. American forces then occupied the country, supporting the creation of a Shi’ite-led government and spent years fighting an insurgency. The US withdrew its forces at the end of 2011, but returned less than three years later following Islamic State’s rapid expansion across Iraq and Syria. Between 2014 and 2017, US-led coalition forces worked alongside Iraqi security forces in a large military campaign which ultimately ended Islamic State’s territorial control in Iraq.
The war came at a significant human cost for the US. Around 4,500 Americans were killed during more than two decades of conflict in Iraq, making it one of the most costly US wars of the 21st century in terms of American military deaths. The US military presence also became closely linked to the wider confrontation between Washington and Tehran. Iraq, one of the few countries able to maintain close political and military relationships with both the US and Iran, was increasingly caught between the two powers.
Tensions flared after the US killed senior Iranian commander Qasem Soleimani in a strike near Baghdad airport in January 2020. Iran-aligned armed groups then launched repeated attacks on US military positions in Iraq while Washington responded with retaliatory operations. Iraq therefore remained an important arena in the US-Iran confrontation as Baghdad attempted to balance its relationships with both countries.
The current withdrawal is especially significant due to occurring in the context of a wider war with Iran. Seven of the 18 US service members listed as killed in this year’s conflict died in Iraq. The latest US military death in Iraq occurred in July when an Army sergeant was killed during the controlled detonation of a drone at a base near Erbil.
The withdrawal was agreed in 2024 under President Joe Biden and is now being implemented by President Donald Trump’s administration. For Iran and its allied armed groups, the end of the American military presence removes a force which for years served as an important counterweight to Tehran’s influence in Iraq. Iranian officials have explicitly welcomed the departure, calling it a victory for the country’s network of allied armed groups, often referred to by Tehran as the “axis of resistance.”
Iranian officials have argued that lasting security can exist in Iraq once American forces leave the country and wider region. Iran-backed groups in Iraq have also presented the withdrawal as the result of their long-running campaign against the US military presence achieving an important objective. Their statements highlight the political emphasis Tehran and its allies place on the end of the American military mission.
However, the departure has also raised concerns inside Iraq regarding what comes after the foreign forces leave. Abdulrahman al-Zobaie, a Sunni tribal leader from Fallujah, said Iraqis want full sovereignty but queried whether the country is entirely prepared to take responsibility for the entire security situation at this juncture. Fallujah, which became one of the main centers of resistance to US-led forces after the 2003 invasion, remains an important symbol of the long conflict.
The concern is not just over Iran’s growing influence, but also that Islamic State could exploit the end of the international coalition’s military mission to rebuild its operational capabilities. Although the group lost its self-declared caliphate and territorial control in Iraq nearly a decade ago, it has retained sleeper cells capable of conducting attacks.
At its peak, Islamic State controlled roughly one-third of Iraq and killed thousands of people during its campaign. Iraqi and Kurdish security officials now warn that the loss of American intelligence, logistical support and drone capabilities could hinder the ability to monitor and disrupt the group’s remaining networks.
Kurdish commander Sirwan Barzani said security officials had witnessed movement by Islamic State sleeper cells during the weeks after the planned withdrawal became widely known. Iraqi security forces have also stated that a suspected Islamic State cell was planning suicide attacks to coincide with the withdrawal. The reports have further underlined concerns that despite its major military defeats, the group still retains the ability to exploit weaknesses in Iraq’s security system.
The Iraqi government has a difficult task ahead as it enters this new phase. Baghdad must bolster its own security institutions while managing the influence of powerful Iran-backed armed groups and preventing Islamic State from exploiting potential security gaps. At the same time, Iraq will have to maintain its relationship with Washington while dealing with its strategically important neighbor, Iran.
The US departure therefore does not only mark the end of an American military story in Iraq. It begins a new period in which Iraqi authorities will have greater responsibility for maintaining national security and balancing competing regional influences. Iran and its allies are likely to see the withdrawal as a significant strategic gain, while Iraqi officials will be under pressure to ensure that the end of the foreign military presence does not create opportunities for armed groups or extremist networks.
For Iraq, the coming months will be a test of how effectively its security forces can operate without the same level of American intelligence, logistics and military support. The country will also need to navigate the political influence of Iran-backed groupsand the threat posed by Islamic State sleeper cells. The US withdrawal ends more than two decades of American military involvement but the security and political consequences of the departure are likely to remain a significant issue for Iraq and the wider Middle East.
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