U.S. Withdrawal Leaves Iraq and Syria Confronting a Lingering ISIS Threat

The United States has finished pulling its forces out of Iraq and Syria, marking the end of a decade of U.S. leadership in the fight against the Islamic State. The phased reduction aimed to prevent a power vacuum that could be exploited by proxy militias, hostile regional powers, terrorist groups, and rival great powers, as occurred previously in Iraq and Afghanistan. Despite its weakened state, ISIS remains active in both countries, requiring Iraq and Syria to develop a lasting regional counterterrorism strategy to keep the group from regaining strength.

While the drawdown lowers U.S. personnel costs and exposure, it also reduces situational awareness of ISIS cells, strains security cooperation, and removes a forward operating base from which Washington can anticipate and interdict threats before they reach American or allied interests.

Although the number of ISIS attacks has dropped in Iraq and Syria since 2025, this reflects a shift in tactics rather than a loss of capability. In Syria, the group has broadened its targeting. In June, it struck oil tankers, trucks, checkpoints, military bases, politicians, judges, and Ministry of Defense buses. In July, a bomb at a Damascus café—popular with Justice Ministry staff—killed ten. Two further explosions during French President Emmanuel Macron’s inaugural state visit claimed ten lives near the Four Seasons Hotel and eighteen near the Ministry of Tourism.

U.S. counterterrorism assets were never flawless, but their departure can cause rapid degradation of those capabilities. The Counter‑ISIS mission has been dismantled and detention facilities such as Al Hol and Al Roj have been emptied. Prisons across the region have also been compromised. As its territorial control dwindled, ISIS began prioritizing prison breaks to rebuild its ranks, echoing earlier campaigns like the 2012‑13 “Breaking the Walls” effort in Iraq.

Iraq faces a severe challenge after taking custody of roughly 5,700 ISIS‑linked prisoners—nationals of Iraq, Syria, and 61 other countries—following the Syrian Democratic Forces’ loss of northeastern Syria in January. Those detainees were placed in facilities already strained by overcrowding and limited resources, and Baghdad assumed responsibility for their confinement, interrogation, and adjudication. The U.S. presence previously helped ensure humane treatment and fair legal processes, limiting ISIS’s ability to exploit prisons for recruitment and operational planning. With the American forces now gone, there are genuine fears that standards may deteriorate.

Syria’s security apparatus is still uncertain whether it can quickly integrate and maintain the gains against ISIS, especially as the group has slipped operatives into the Syrian Army and orchestrated high‑profile attacks outside its historic strongholds. Syrian detention centers have become flashpoints for prison breaks, such as the 2022 assault on Al Sinaa prison and a January incursion at the Shaddadi facility.

During the campaign against extremist groups in Iraq and Syria, U.S. personnel supplied intelligence, surveillance, reconnaissance, air support, special‑operations capabilities, logistics, and partnership frameworks to local forces. This collaboration enabled the United States and its allies to track and neutralize entities such as the Islamic State, ultimately dismantling its territorial caliphate, while also providing Washington with direct insight into evolving terrorist tactics and the broader political‑security environment.

Without those assets, ISIS activity is expected to rise in both frequency and lethality. The United States, its allies, and the Iraqi and Syrian governments will need innovative approaches to plug the emerging security voids. Neighboring states—Jordan, Türkiye, Lebanon, and other regional actors—should deepen ties with Damascus and Baghdad. Failure to do so could erase years of counterterrorism gains, potentially compelling the United States to re‑engage.

Caroline D. Rose is a Senior Director at the New York City‑based Soufan Center, a nonpartisan research institution, where she conducts research on the crime‑terror nexus, security, counterterrorism, and U.S. defense policy with a focus on Iraq and Syria. She is a Senior Nonresident Fellow at both the New Lines Institute and Orion Policy Institute, where she writes about trends in terrorism and geopolitics.

Dr. Julie Chernov Hwang is an Associate Professor of Political Science and International Relations at Goucher College. She is a Senior Research Fellow at the Soufan Center and a Harry Frank Guggenheim Distinguished Scholar with over a decade researching terrorist behavior, notably social networks, radicalization, commitment, role assignment, disengagement, rehabilitation, reintegration, repatriation, and deradicalization.

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