The US-led coalition formally ended its Operation Inherent Resolve mission in Iraq on September 30 as its remaining forces and equipment completed their withdrawal, shifting primary security responsibility to Baghdad and raising new questions about how Iraq and Syria will monitor their long frontier against ISIS.
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US Central Command said the transition was part of a planned move toward a bilateral defense relationship between Washington and Baghdad. Combined Joint Task Force-Operation Inherent Resolve remains active, with its headquarters relocated to Jordan, while coalition forces continue counter-ISIS operations in Syria.
For Damascus, the shift follows another major change. US forces completed their departure from the al-Tanf garrison in southeastern Syria in February as part of a broader military repositioning. CENTCOM said at the time that American forces would remain capable of responding to ISIS threats in the region and supporting partner-led operations.
The transition raises a central question along the Syrian-Iraqi frontier: Can forces on both sides maintain effective surveillance and intelligence sharing as the coalition’s military footprint changes?
Istanbul-based Iraqi journalist Ali al-Khazali told The Media Line that the most important change after the coalition mission ended has not been a major increase in troop numbers, but a higher state of readiness and greater responsibility for Iraqi forces.
Before the transition, he said, Iraq had worked to build a multilayered defensive system along the Syrian border involving border guards, the Iraqi army, and the Popular Mobilization Forces, backed by fortifications and aerial and technical surveillance.
“Baghdad tried before the coalition’s departure to make the border less dependent on the foreign military presence and to ensure that Iraqi forces themselves hold the ground and manage the file directly,” al-Khazali said.
Iraqi authorities had already expanded concrete barriers, trenches, barbed wire, thermal cameras, observation towers, and drone surveillance along the frontier.
Stronger fortifications, al-Khazali said, do not mean Baghdad can fully replace everything the coalition provided.
Iraqi forces are now capable of handling much of the operational burden inside the country and conducting operations against ISIS cells, he said, but advanced technical and intelligence capabilities remain a more difficult challenge.
US capabilities difficult to replace in short term by Iraq
According to al-Khazali, the United States provided aerial surveillance, drones, intelligence imagery, and sophisticated systems for tracking targets and rapidly integrating information from multiple sources - capabilities that will be difficult to replace completely in the short term.
“Iraq can compensate for a large part of the coalition’s military role, but it has not yet reached the point where it can fully dispense with US support, particularly in intelligence, surveillance, and long-range reconnaissance,” he said.
On the Syrian side, political analyst Firas al-Allawi described similar concerns about surveillance and intelligence capabilities.
Al-Allawi told The Media Line that there are no clear indications of a broad Syrian military deployment or a major increase in troop numbers along the Iraqi border, although limited redeployments may have taken place recently.
“What is available so far does not indicate the transfer of large numbers of troops or major changes along the Syrian-Iraqi border,” al-Allawi said.
Coordination between Damascus and Baghdad exists, particularly in the exchange of security information, he said, but it has not yet reached the level of an integrated strategic security partnership.
Al-Allawi believes some intelligence cooperation is taking place away from public view, with a significant portion occurring within a broader framework that still involves the United States.
“I believe an important part of the information exchange takes place within a broader intelligence cooperation umbrella in which Washington participates, rather than through deep, direct Syrian-Iraqi cooperation,” he said.
A degree of mistrust and caution remains between Damascus and Baghdad, according to al-Allawi, making it premature to describe their cooperation as a fully developed joint security system.
Al-Khazali offered a similar assessment from the Iraqi side. Direct communication channels, information sharing, and meetings between border officials exist, he said, but publicly available information does not indicate that the two countries operate a permanent joint operations room or fully integrated intelligence center.
“What exists is direct communication channels, information exchange, and coordination in some operations,” he said. “But transforming that cooperation into a permanent joint security system is still a work in progress.”
Iraqi officials have previously said Baghdad coordinates directly with Syrian authorities to prevent ISIS infiltration, combat smuggling, and exchange security information.
ISIS operating through small cells, individual operatives, in shift since 2014
The nature of the threat has also changed considerably since 2014.
ISIS no longer needs to move large columns of fighters across the border or capture cities and crossings to pose a danger. The group can operate through smaller cells, desert routes, logistical and financial networks, and individual operatives capable of exploiting gaps in surveillance without the kind of large-scale military breakdown seen during its territorial expansion.
“The most dangerous gap today is not an open stretch of border or the collapse of fortifications,” al-Khazali said. “The biggest danger is the intelligence gap between the two sides of the border.”
The desert corridor between Iraq’s Anbar province and Syria’s Deir ez-Zor region remains particularly sensitive, he said, because small cells and smuggling networks can exploit vast distances and the difficulty of maintaining continuous surveillance.
Al-Allawi identified a similar weakness on the Syrian side.
Syria’s Badia desert and the broader desert belt extending toward Iraq still suffer from limited aerial surveillance and incomplete intelligence capabilities, he said, while the vast geography makes sustained control difficult.
“The area generally remains fragile from both a security and strategic perspective, and the length of the Syrian-Iraqi border makes it even harder to control,” al-Allawi said.
Increasing troop numbers insufficient to rein in ISIS, analyst says
Although ISIS is far weaker than at the height of its territorial expansion, scattered cells in desert areas could use surveillance gaps to regroup or move personnel, money, and equipment.
For that reason, al-Allawi said increasing troop numbers alone will not be enough. Syria needs more advanced surveillance and reconnaissance technology, aerial support, improved equipment, and personnel with greater training in border security, counter-infiltration, and desert operations.
Al-Allawi said improved border security will also require broader cooperation with Iraq, the United States, the international coalition, and Jordan rather than relying solely on a larger Syrian military deployment.
The ISIS detainee issue further ties Syrian and Iraqi security together.
During a 23-day operation that began January 21, US forces transferred more than 5,700 adult male ISIS detainees from facilities in northeastern Syria into Iraqi custody. CENTCOM said the operation was intended to keep the detainees securely held and reduce the risk of an ISIS resurgence.
The end of the coalition mission in Iraq does not sever Iraq’s security concerns from Syria. Iraq now has responsibility for thousands of ISIS detainees transferred from Syrian facilities, while Damascus must prevent remaining ISIS cells in the Badia from using the frontier for movement and reorganization.
Iraqi and Syrian sources agree on one central point: Securing the frontier depends not only on walls, trenches, troops, and surveillance equipment, but on whether information can cross the border faster than ISIS operatives do.