The anti-ISIS campaign and the residual insurgency
A caliphate destroyed in five years, an insurgency that has outlasted it by seven, and a detention system nobody wanted to inherit.
The coalition-backed campaign that destroyed the Islamic State's territorial caliphate between 2014 and 2019, and the desert insurgency and detention system it left behind. Its achievement and its liability are the same thing: the forces that won it were made indispensable by the prisons and camps they still hold.
Summary
A US-led coalition began air operations in Syria in September 2014, and the defence of Kobani that winter made the Kurdish-led YPG its ground partner of choice. The Syrian Democratic Forces were formed in October 2015 as a YPG-led, Arab-inclusive umbrella, and with coalition air power and special forces ground the caliphate out of its cities: Manbij, Raqqa in October 2017 after a battle that destroyed much of the city, the Euphrates valley towns, and finally Baghouz in March 2019. What remained was an insurgency — desert cells, assassination campaigns around Deir ez-Zor, and a declared ambition to break the prisons — alongside a detention archipelago holding thousands of fighters and tens of thousands of family members in the al-Hol and Roj camps. Attacks fell sharply after the January 2026 settlement closed the seams between competing security authorities; the United States completed its withdrawal in April 2026, and ultimate responsibility for the detention system is moving toward the state.
Why it matters
This campaign built the northeast's twin inheritance — the international standing that made a decade of Kurdish-led autonomy possible, and the prisons and camps that made it unavoidable — and both are now being handed to the Syrian state. It is also the reason detention and camp files in this module are security files as well as humanitarian ones, and the reason the module treats the post-2026 fall in attack tempo as reversible: the insurgency's health has tracked the gaps between rival authorities more closely than its own strength.
Stated objectives
What the participants say. Each entry cites where the position was stated; Vigil records that it was made, not that it is true.
The coalition stated its objective as the enduring defeat of the Islamic State, initially through air support to partner ground forces and later through the recapture of its territory.
Kurdish-led authorities have stated that responsibility for the detention and camp system requires continued international support and repatriation by countries of origin, and that the file cannot be closed locally.
Assessed objectives
Vigil's reading, graded. Kept structurally apart from stated positions so an assessment can never be published as someone's declared aim.
Destroy the organisation's territorial project without committing Western ground forces, by substituting local partners and air power — an approach that succeeded on its own terms and created the political problem the northeast has been managing since.
Since 2019, contain rather than eliminate: keep attack tempo suppressed and the detention system secure at sustainable cost, in the absence of any political solution to the population it holds.
Primary forces
- Syrian Democratic Forces (SDF) Primary force · Confidence: High · as of 2026-07
- Syrian state forces (Ministry of Defence) Primary force · Confidence: Moderate · as of 2026-07
Assumes responsibility for the counter-insurgency and, ultimately, the detention file under the January 2026 agreement. Capacity for it is untested, which is why the edge is graded moderate.
Opposing forces
- ISIS remnants (Syria) Opposing force · Confidence: High · as of 2026-07
Supporting & external
- US anti-ISIS mission in Syria — historical Supporting force · Confidence: High · as of 2026-04
Air power, special forces and enabling support from September 2014 until the completion of the US withdrawal in April 2026. Recorded as a historical presence; residual influence runs through diplomacy.
- Asayish (internal security forces) Supporting force · Confidence: Moderate · as of 2026-07
Custody and internal security across the detention and camp system, which is the campaign's standing commitment rather than an operational role.
Phases
Air campaign and the partnership at Kobani
Coalition air operations began in September 2014, and the defence of Kobani through that winter made the YPG the partner of choice. The Syrian Democratic Forces were formed in October 2015 as the umbrella built to take the caliphate down.
The cities, and the end at Baghouz
Manbij, then Raqqa in October 2017 after a battle that destroyed much of the city, then the Euphrates valley towns, and finally Baghouz. The territorial caliphate ended; the destruction and the detained population it left behind did not.
Insurgency, prisons and camps
Desert cells, assassination campaigns around Deir ez-Zor and a declared ambition to break the prisons, alongside a detention archipelago the world declined to repatriate and the region could not absorb. Containment, not resolution.
Transfer of responsibility
Attacks fell sharply after the January 2026 settlement closed the seams between competing authorities. The United States completed its withdrawal by April 2026, and ultimate responsibility for counter-insurgency and for the detention system moves toward the state.
Outcome and present status
The territorial objective was achieved in March 2019 and the campaign has been open ever since. The organisation persists as a desert insurgency whose tempo has tracked the gaps between rival security authorities more reliably than its own strength, and it fell sharply after those gaps closed in January 2026 — which is why the module treats the improvement as reversible rather than structural. The detention and camp system remains, repatriation remains stalled, and the responsibility for both is transferring to a state whose capacity has not been tested against it.
Observed adaptations
A shift by the organisation from holding ground to dispersal, ambush and assassination after 2019, exploiting a ground in which space substitutes for sanctuary and small groups cost almost nothing to sustain.
Concentration of effort on prisons and camps as the organisation's declared route to regeneration, which is what makes the detention file a security question rather than only a humanitarian one.
On the counter-insurgency side, a shift from partnered clearing operations to a single national security authority — removing the seams between rival forces that the insurgency had exploited, at the cost of an untested capability replacing an experienced one.
Political implications
The campaign created the Kurdish-led international standing that made a decade of autonomy possible, and the liability that made its end negotiable.
Military implications
A dispersed insurgency in open ground responds to sustained presence rather than to operations, which makes the transfer of responsibility a question of endurance rather than of capability alone.
Humanitarian implications
Tens of thousands of people, mostly women and children, remain in camps whose ultimate responsibility is changing hands while repatriation stays politically stalled.
Linked events
Locations
Places this module already publishes as map markers, listed because the campaign is about them. Not an operational area.
What remains unknown
- Estimates of the organisation's remaining strength vary by an order of magnitude across published sources. This module publishes none and this record makes no claim about size.
- Attack attribution in the desert is weak: remote incidents are routinely claimed, denied or left unattributed, and published counts conflate very different levels of capability.
- Camp and detention populations are deliberately reported at low precision in this module — populations shift, counts vary between agencies, and no facility-level information is published anywhere.
- The state's actual counter-insurgency capacity in the east is untested and is not assessable from what is currently published.
Readings the evidence also supports
- The post-January 2026 fall in attack tempo can be read as the closing of exploitable seams between rival authorities, as genuine attrition of the organisation, or as a deliberate pause by it while the security landscape reorganises. The module favours the first because the fall coincided with the settlement rather than with any operation, but the reporting does not exclude the others.
- The persistence of the insurgency can be attributed principally to the terrain, to the unresolved detention population, or to the grievances of the Arab-majority east under a Kurdish-led administration. Assessments differ, and the three imply different remedies.
Listed because the record's own assessment is not the only one its sources permit — not as a hedge on the assessment above.
What to watch
Attack tempo against the seams, not the totals
Whether attacks concentrate where security responsibility is changing hands is a better measure of the insurgency's health than the raw count.
Prison and camp security under new management
Custody arrangements, population trends at al-Hol and Roj, and repatriation tempo as responsibility shifts under the integration agreement.
Whether integration friction reopens the seams
The 2026 improvement followed the closing of gaps between rival authorities. Friction in the civilian integration files is the most likely route to reopening them.