Fighting broke out a day after a sweeping integration deal agreed responsibility for prisons housing ISIS detainees was to be transferred to Syria`s government.

Syrian government forces launch a rocket towards Kurdish forces in the Tabqa region of northern Syria on Saturday.Omar Haj Kadour / AFP - Getty Images

The Kurdish-led Syrian Democratic Forces said on Monday that an "armed group" was attacking Shaddadi prison in Hasaka in Syria‘s northeast where it said thousands of Islamic State militants were being held.

The SDF had said earlier in the day it was clashing with Syrian government forces near Al-Aqtan prison on the outskirts of the city of Raqqa that also held IS detainees. Raqqa was once the seat of a short-lived IS-declared "caliphate" in the region.

The SDF described the clashes as a "highly dangerous development" and said government forces seizing the prison "could have serious security repercussions that threaten stability and pave the way for a return to chaos and terrorism."

Under a sweeping integration deal agreed on Sunday, responsibility for prisons housing ISIS detainees was meant to be transferred to the Syrian government which was also expected to take almost full control of the country and dismantle the Kurdish-led forces that controlled the northeast for over a decade.

The agreement came after tensions between government forces and the SDF boiled over earlier this month, eventually resulting in a major push by government forces toward the east. The SDF appeared to have largely retreated after initial clashes on a tense front line area in eastern Aleppo province.

Hours after the government announced the deal, SDF leader Mazloum Abdi confirmed it in a video statement, saying the group had accepted the agreement, which stipulates their withdrawal from Raqqa and Deir el-Zour provinces "to stop the bloodshed."

"We will explain the terms of the agreement to our people in the coming days," he said.

Syria`s Defense Ministry said it ordered the fighting to halt on the front lines after the agreement was announced.

Syria`s new leaders, since toppling Bashar Assad in December 2024, have struggled to assert their full authority over the war-torn country. An agreement was reached in March that would merge the SDF with Damascus, but it didn`t gain traction as both sides accused each other of violating the deal.

Since the push, the government has largely asserted control of the Deir el-Zour and Raqqa provinces, critical areas under the SDF that include oil and gas fields, river dams along the Euphrates, and border crossings.

Syria`s state-run news agency SANA showed President Ahmad al-Sharaa signing and holding the agreement. Abdi, who was scheduled to meet with the president in Damascus was not seen, though his signature appeared on the document. Al-Sharaa told journalists that Abdi could not travel due to bad weather and will visit Damascus on Monday.

"It`s a victory for all Syrians of all backgrounds," al-Sharaa told journalists in Damascus after signing the agreement. "Hopefully Syria will end its state of division and move to a state of unity and progress."

The two warring sides are key allies of Washington. U.S. Envoy Tom Barrack met with al-Sharaa earlier Sunday as government forces were sweeping into the city of Raqqa and across Deir el-Zour province. Abdi reportedly joined the meeting over the phone.

Barrack praised the agreement, saying it will lead to "renewed dialogue and cooperation toward a unified Syria," ahead of working on the details of implementing the integration.

"This agreement and ceasefire represent a pivotal inflection point, where former adversaries embrace partnership over division," said Barrack in a post on X.