ISIS in Syria and Iraq: Why the 2026 Numbers Contradict the Resurgence Story
SDF integration, a US withdrawal, and a 7,000-detainee transfer reshaped the risk map — and attacks collapsed, not climbed
Eight attacks. Four deaths. That was the Islamic State's entire recorded output across Syria in May 2026 — a fraction of the roughly 29 attacks and 15 deaths per month the group averaged just one year earlier. Anyone still bracing for the "ISIS resurgence" that dominated headlines through 2024 and 2025 is fighting the last war. The real story of 2026 is stranger and more consequential: the collapse of the Syrian Democratic Forces as an independent military actor, and the withdrawal of American troops, did not open the door for the Islamic State. They slammed it shut.
That doesn't mean the threat has vanished. It means the threat has moved — into detention camps, across a porous Iraqi border, and into the hands of Iran-aligned militias exploiting the same power vacuum for entirely different reasons.
| Metric | 2025 average (monthly) | May 2026 |
|---|---|---|
| ISIS-claimed attacks | ~29 | 8 |
| Fatalities from ISIS attacks | ~15 | 4 |
| Share of attacks in former SDF territory | ~90% | Sharply reduced post-integration |
The Detention Time Bomb Washington Defused — For Now
The single biggest wildcard in the entire Syria-Iraq security picture has never been ISIS's battlefield capacity. It has been the roughly 10,000 detained fighters and thousands of their family members held in makeshift Syrian facilities like Al-Hol, originally guarded by the SDF. When Damascus took direct control of those sites earlier this year, U.S. Central Command scrambled to prevent a mass breakout, transferring an initial 150 high-risk detainees out of Hasakah in January 2026, with plans eventually covering up to 7,000 individuals moved into Iraqi custody.
Estimates of the group's manpower diverge wildly depending on who is doing the counting. Iraq's own intelligence chief has floated figures as high as 10,000 fighters regrouping inside Syria — a number the U.S. military has not corroborated and the latest United Nations Security Council report puts closer to 3,000 fighters total across both countries. That gap between an alarmed Baghdad and a more measured UN assessment is itself a story: it reflects how differently regional and international actors are reading the same fragile transition.
Why the SDF's Collapse Backfired on ISIS, Not the State
For most of 2025, nearly nine in ten ISIS attacks landed inside territory run by the Kurdish-led Syrian Democratic Forces — not because the SDF was weak on counterterrorism, but because Arab communities under its rule resented a governing structure they saw as ethnically exclusionary. That resentment, not ideology, was ISIS's real recruiting pitch.
Then, in January 2026, the SDF's position unraveled. Four Kurdish brigades, roughly 5,200 soldiers, were absorbed into Syria's Ministry of Defense; another 10,000 Kurdish local security personnel, including at least a thousand women, moved under the Ministry of Interior. Analysts who track the group attack-by-attack recorded a 17% drop in ISIS operations in the months that followed — then a further 67% collapse once American forces completed their withdrawal from Syrian soil in February. The logic is almost counterintuitive: removing the governing structure Arab tribes resented removed ISIS's grievance-based recruiting pool along with it.
A Different Kind of Infiltration
Syria's interior minister, Anas Khattab, spent years running networks of infiltrators inside ISIS cells during his time fighting the group in Idlib. That tradecraft has reportedly produced real intelligence wins — including the capture of ISIS's Syria-wide operational commander in a string of raids spanning late December 2025 into January 2026. It is an uncomfortable irony of the post-Assad transition: some of the men now dismantling ISIS cells learned their craft inside the same insurgent ecosystem they are now hunting.
Iraq's Parallel Withdrawal Creates a Second Front
While Syria's security picture has been reshaped by state collapse and rebuilding, Iraq's has been reshaped by simple attrition of foreign support. American forces completed their pullback from Ain al-Asad air base in January 2026, and the wider Global Coalition mission is winding down on a similar late-2026 timeline. Iraq's own intelligence chief, Hamid al-Shatri, warned in January that the deteriorating security architecture in northeastern Syria poses a direct spillover risk to Anbar and Mosul — precisely the provinces where ISIS built its original caliphate a decade ago.
Militias Filling a Different Vacuum
ISIS is not the only actor exploiting the security gap left by departing coalition forces. Iran-aligned militia groups have used drone strikes on Iraqi energy infrastructure — including a November 2025 attack on the Khor Mor gas field — to signal continued relevance and deter foreign investment, all while invoking a "resistance" narrative that has far more to do with domestic political leverage in Baghdad than with fighting the Islamic State.
Recalibration, Not Resurgence
The Soufan Center's own June 2026 assessment lands on a phrase worth sitting with: ISIS in Syria is undergoing "not resurgence, but recalibration." Attack numbers are at a historic low for the year, yet analysts caution against reading that as neutralization, given the still-unresolved detainee question and scattered evidence of ISIS infiltration attempts inside Syrian security agencies themselves.
That ambiguity is precisely why the old "escalating insurgency" framing, popular through 2024 and 2025, no longer fits what the data shows in mid-2026. The threat hasn't been defeated. It has been pushed into a narrower, more brittle set of pressure points — detention facilities, a stretched Iraqi security service, and a border region that no longer has an American troop presence backstopping it.
Frequently Asked Questions
Sources & References
- The Soufan Center — "Not Resurgence, but Recalibration: ISIS in Syria," IntelBrief, June 2026
- Middle East Institute — "The Collapse of ISIS in Syria," 2026
- Karam Shaar Advisory — "From Resurgence to Retrenchment: The Evolution of ISIS After Assad's Fall," January 2026
- The Washington Post — "ISIS threat spiking as militant ranks in Syria swell, Iraqi official says," January 2026
- SpecialEurasia — "Iraq: Security Risk Assessment and Terrorist Threat in 2026," February 2026
- Small Wars Journal (Arizona State University) — "Preventing ISIS' Rising Resurgence After Syria's Power Shift," March 2026
- Foreign Affairs — "The Return of ISIS: The Group Is Rebuilding in Syria," September 2025
- World Bank — Syria Economic Monitor, 2025