Fighting in north-east Syria sorely tested a day-old ceasefire on Monday as Kurdish forces resisted a government takeover in the region.
Dozens of people were reported killed in clashes between the army and the Kurdish-led Syrian Democratic Forces. ISIS supporters were feared to have escaped custody during fighting near their prison.
SDF resistance foiled the Syrian government's hopes of a smooth advance into territory long held by the Kurdish group, under a deal announced on Sunday. The SDF said it came under fire from artillery and Turkish drones.
The SDF accused pro-government fighters of attacking a prison holding thousands of ISIS detainees. It said dozens of its fighters were killed and that the Al Shaddadi prison had "fallen outside the control of our forces".
The Syrian army, in turn, said three of its soldiers were killed in attacks by Kurdish militants. It accused "terrorist groups" of "attempting to disrupt the implementation of the ceasefire", and the SDF of using ISIS warnings to exert pressure.
In the evening, the Syrian army announced it had taken control of the city of Shaddadi and its prison, and was “immediately launching operations to secure the area and arrest fleeing ISIS elements who were released by the SDF".
Footage showed Syrian army forces in the city, where they announced a “complete curfew”.
But renewed clashes in the evening further threatened the fragile truce. Despite the ceasefire, Syria army’s advance into the Hasakah region was met with resistance from the SDF.
“Turkish drones recently carried out an airstrike on Mount Kazwan, south of the city of Hasakah, while the site was also subjected to artillery fire,” said SDF spokesman Farhad Shami. He added that the forces repelled attacks by Damascus near Al Aliya village, “inflicting heavy losses in personnel and equipment".
In northern Raqqa, Mr Shami said that forces loyal to Damascus was shelling the Al Aqtan Prison, which he said held ISIS members and leaders. The prison is one of the last SDF-controlled positions in Raqqa which the Syrian forces have yet to take over.
“Our forces are showing strong resistance against the attacks," he said.
Syrian forces regained large areas of territory from the SDF over several days, including two Arab-majority provinces – Raqqa, home to major hydroelectric dams, and the oil-rich area of Deir Ezzor, in a rapid eastward expansion into SDF-controlled territory.
In Raqqa, government checkpoints have replaced SDF ones, as security forces were posted across the city, where they were warmly welcomed by residents. SDF flags and pictures of its leaders littered the ground, and symbols of the Kurdish-led forces at checkpoints were torn down.
SDF rule had been marked by growing discontent in Arab-majority areas, with many residents saying they felt oppressed under Kurdish-led authorities.
In Raqqa, people were seen crossing the two banks of the Euphrates by boat after the SDF destroyed two bridges in the area, marking the end of what had traditionally delineated the border with the SDF.
After weeks of unrest, the government announced a wide-ranging deal with the SDF on Sunday to bring Kurdish civilian and military authorities under state control. The Kurdish-led group agreed to cede control of Deir Ezzor and Raqqa provinces to the Syrian government on Sunday after the army's lightning offensive into the two oil-rich provinces.
After Deir Ezzor and Raqqa, convoys of Syrian forces were sent on Monday to Hasakah. Under the agreement, Hasakah civilian institutions are to be integrated into Syria’s central government.
Syrian forces have yet to take control of the entire governorate or enter the city. Reports said SDF fighters were withdrawing to Qamishli, further north, a predominantly Kurdish city.
The SDF, whose leader Mazloum Abdi vowed to protect gains made by the Kurdish region, said pro-government fighters "continue their attacks" in areas including Raqqa.
Mr Abdi said the forces had agreed to withdraw from the two provinces but remained committed to protecting the “achievements” the Kurdish region had made.
“This war was imposed on us. We wanted to prevent it, but unfortunately, because it was planned by many forces, it was imposed on us,” he said in a video message broadcast by Kurdish media.
“It was planned to become a civil war, but to avoid this and prevent further meaningless bloodshed, we agreed to withdraw from Deir Ezzor and Raqqa to Hasakah. An agreement was signed on this.”
The Syrian military, in turn, accused militants including members of the Kurdistan Workers' Party (PKK) of attacking its forces on Monday.
The SDF and the Syrian government had been engaged in months of talks aimed at bringing Kurdish-run institutions under the state but discussions had faltered by the end of 2025. After the end-of-year deadline passed, clashes broke out and grew into a government offensive on Kurdish-held areas. Sunday's agreement said the clashes should end, although intermittent fighting was still reported in some areas.
The SDF was backed by the US during the fight to win back ISIS-held territory in Syria, but the Americans have since "informed the Kurdish leadership that they must hand over these areas and withdraw", a Syrian political source said.
The SDF "had been betting on time" and "hoped to apply as much pressure as possible and convince local communities in Deir Ezzor and Raqqa to move with them in a partnership", the source said. "What became clear is that they did not succeed."
A Syrian-Kurdish military source said the SDF still has about 100,000 fighters who are well-trained and well-equipped, and said the group's pull-back was "not the result of real battles".
They said the agreement "is vulnerable to collapse or failure because it is difficult to imagine a convincing mechanism for absorbing tens of thousands of Kurdish fighters into a government army led by figures linked to the extremist Hayat Tahrir Al Sham", the former rebel group that seized power in 2024.
"The agreement did not specifically address the fate of the Kurdish Women’s Protection Units affiliated with the SDF, nor how oil and gas revenue reclaimed by Al Shara’s government would be divided, nor what allocations and rights Kurdish areas would receive, beyond the announcement of the appointment of a Kurdish governor for Hasakah."
Mr Abdi's remarks came hours after President Al Shara announced the signing of the agreement. US envoy Tom Barrack said it was a “pivotal inflection point”, but that there was still challenging work to be done to finalise details of a comprehensive integration deal.
That did appear to offer some concessions. It said the SDF could nominate military and civilian figures to assume leading roles in the central government and that Hasakah province, which has a sizeable Kurdish population and is the main stronghold of the SDF, would have a governor appointed by consensus.
