Government troops have seized swathes of northern and eastern territory in the last two weeks from the Kurdish-led Syrian Democratic Forces in a rapid turn of events that has consolidated President Ahmed al-Sharaa's rule.
Sharaa's forces were closing in on the last SDF strongholds earlier this week when he abruptly announced a ceasefire, giving them until Saturday night to lay down arms and come up with a plan to integrate with Syria's army - or to resume fighting.
Earlier on Saturday, a Syrian official said the SDF had not responded to the government's attempts to reach out, while the SDF accused the government of moving towards escalation in a "systematic manner" through military build-ups.
However, about an hour before midnight, Syria's defence ministry announced that its forces would cease military operations for a further 15 days to support an ongoing US operation to transfer Islamic State detainees from Syria to Iraq.
The SDF said in a statement the agreement has been reached through international mediation, "while dialogue with Damascus continues".
The new ceasefire took effect at 11pm (7am AEDT Sunday).
The US has been engaging in shuttle diplomacy to establish a lasting ceasefire and facilitate the integration of the SDF - which for years was Washington's main partner in Syria - into the state led by its new favoured ally, Sharaa.
Senior US and French officials have urged Sharaa not to send his troops into remaining Kurdish-held areas, fearing renewed fighting could lead to mass abuses against Kurdish civilians, diplomatic sources told Reuters.
Government-affiliated forces killed nearly 1500 people from the Alawite minority and hundreds of Druze people in sectarian violence last year, including in execution-style killings.
Amid the instability in the northeast, the US military has been transferring hundreds of detained fighters from the Islamic State group from Syrian prisons formerly run by the SDF across the border into Iraq.
As the Saturday deadline approached, SDF forces had reinforced their defensive positions in the cities of Qamishli, Hasakeh and Kobane for a possible fight, Kurdish security sources told Reuters.
The possible showdown is the culmination of rising tensions over the last year.
Sharaa, whose forces toppled longtime ruler Bashar al-Assad in late 2024, has vowed to bring all of Syria under state control - including SDF-held areas in the northeast.
But Kurdish authorities who have run autonomous civilian and military institutions there for the last decade have resisted joining up with Sharaa's Islamist-led government.
After a year-end deadline for the merger passed with little progress, Syrian troops launched the offensive this month.
They swiftly captured two key Arab-majority provinces from the SDF, bringing key oil fields, hydroelectric dams and some facilities holding Islamic State fighters and affiliated civilians under government control.
36°C