The SDF, which controls much of Syria’s northeast, signed an agreement to join Syria’s new state institutions, the Syrian presidency said on Monday.

“The US welcomes the recently announced agreement between the Syrian interim authorities and the Syrian Democratic Forces to integrate the northeast into a unified Syria,” Rubio said in a statement.

“The US reaffirms its support for a political transition that demonstrates credible, non-sectarian governance as the best path to avoid further conflict. We will continue to watch the decisions made by the interim authorities, noting with concern the recent deadly violence against minorities,” Rubio added.

The accord provides for SDF-controlled civilian and military institutions in northeast Syria to be integrated with the state, and for border crossings, an airport, and oil and gas fields there to come under the Damascus administration’s control.

The accord comes at a critical moment for Damascus as it grapples with the fallout from mass killings of Alawite minority members in western Syria – violence that Syrian President Ahmed al-Sharaa said on Monday threatened his effort to unite Syria after 14 years of conflict.

Pressure has been growing on Syria’s Islamist-led government to investigate after reports by witnesses and a war monitor of the killing of hundreds of civilians in villages where the majority of the population are members of ousted President Bashar al-Assad’s Alawite sect.