The withdrawal marks a strategic shift, potentially bolstering Iranian influence and raising the spectre of ISIS resurgence.
Overview
On 30 September 2026, Operation Inherent Resolve (OIR), the US-led military intervention against Islamic State of Iraq and the Levant (ISIL), formally concluded with the withdrawal of remaining US troops from northern Iraq. Launched in October 2014, OIR successfully dislodged ISIL from significant territorial holdings in Iraq and Syria. However, the cessation of this operation does not equate to the defeat of ISIL, and its end raises complex questions regarding regional stability, the future of US-Iraq relations, and the potential for a resurgent insurgency. This analysis examines the historical context, key actors’ positions, and potential implications of OIR’s termination, offering an outlook on likely developments in the region.
Historical Context
The rise of ISIL in 2014, exploiting political instability in post-invasion Iraq and the Syrian Civil War, presented a major security challenge. The group rapidly seized large swathes of territory, establishing a self-proclaimed caliphate and attracting foreign fighters. In response, the US formed a broad coalition, launching OIR to degrade and ultimately defeat ISIL’s territorial control.
The intervention involved extensive air strikes, special operations, and the provision of training and equipment to local partners – primarily the Iraqi Security Forces (ISF) and the Syrian Democratic Forces (SDF). While OIR succeeded in reclaiming physical territory, it operated amidst a complex geopolitical landscape, notably the escalating proxy conflict between the US and Iran. The US military presence in Iraq, particularly, became a focal point of tension, with Iran-backed militias repeatedly targeting US personnel and facilities. This culminated in a gradual draw-down of US forces, culminating in the complete ending of OIR.
Key Actors & Positions
Several key actors are shaping the post-OIR landscape. The United States views the end of OIR as a testament to the success of the coalition in degrading ISIL’s capabilities. However, Washington retains concerns about the group’s continued ideological influence and potential for resurgence. Its position is increasingly focused on shifting towards diplomatic and economic engagement in Iraq, contingent on the Iraqi government’s ability to curb the influence of Iranian-backed militias.
Iraq’s Shiite political elite largely welcomes the end of OIR, framing it as a restoration of Iraqi sovereignty. They seek to redefine their relationship with the US, prioritising economic ties. However, the Iraqi government faces a significant challenge in balancing its relationship with both Washington and Tehran.
Syria remains deeply fractured. The Syrian government, backed by Russia and Iran, views the US withdrawal as a positive development but continues to grapple with instability and the presence of various armed groups. The Syrian Democratic Forces (SDF), a key US partner in the fight against ISIL, feel vulnerable following the US withdrawal, fearing increased pressure from Turkey and the Syrian government.
Iran stands to gain from the diminished US military presence. Its network of proxies in Iraq and Syria is likely to expand its influence, potentially exacerbating regional tensions. ISIL, despite territorial losses, remains a potent threat, actively operating as an insurgency in both countries and seeking to exploit the security vacuum created by OIR’s termination.
Analysis
The end of OIR presents a complex set of implications. While the immediate threat of ISIL controlling large territories has diminished, the group retains the capacity to conduct attacks and inspire affiliates globally. A reduced US military footprint could create opportunities for ISIL to regroup and exploit political and security vacuums in Iraq and Syria. This risk is heightened by the potential for renewed conflict between various actors within these states.
The US withdrawal intensifies existing risks for Kurdish communities in Syria and Iraq, who have been vital partners in the fight against ISIL. They now face increased vulnerability to attacks from Turkish forces in Syria and the potential for abandonment by the Iraqi central government.
Furthermore, the end of OIR is likely to embolden Iran and its proxies in the region. Increased Iranian influence in Iraq could further destabilise the country, undermining its sovereignty and potentially provoking a more direct confrontation with the US. The future of US-Iraq relations hinges on Baghdad’s willingness and ability to address the threat posed by these militias, a prospect complicated by Iraq’s close economic ties with Iran. The US has indicated it may reassess its engagement with Iraq should the militias remain unchecked.
Outlook
In the short term, a surge in ISIL attacks in both Iraq and Syria is probable, though likely constrained to asymmetric warfare. The group will seek to exploit security gaps and capitalise on local grievances.
The Iraqi government will likely attempt to navigate a delicate balancing act between Washington and Tehran, seeking to maintain economic ties with both countries while attempting to contain the influence of Iran-backed militias. Success is far from guaranteed.
The SDF in Syria face an increasingly precarious situation and will likely seek alternative security guarantees, possibly from Russia or the Syrian government, despite potential risks associated with such alliances.
The US is unlikely to fully disengage from the region, maintaining a presence through intelligence gathering, limited special operations, and continued support to partner forces. However, the era of large-scale military intervention appears to be over, replaced by a strategy focused on over-the-horizon capabilities and diplomatic engagement. The coming months will be critical in determining whether the gains made against ISIL are sustained or if the group will once again pose a significant threat to regional and international security.
Sources:
War on the Rocks. (2026, September 22). What the End of Operation Inherent Resolve Means for Iraq and Syria. [https://warontherocks.com/2026/09/what-the-end-of-operation-inherent-resolve-means-for-iraq-and-syria/](https://warontherocks.com/2026/09/what-the-end-of-operation-inherent-resolve-means-for-iraq-and-syria/)
