ERBIL, Kurdistan Region of Iraq – The United States has accelerated its gradual withdrawal from two military bases in eastern Syria’s Deir ez-Zor, one of which is the largest US base in Syria, according to a war monitor.

Rami Abdulrahman, director of the Syrian Observatory for Human Rights (SOHR), told The New Region on Monday that “over the past few hours, US forces carried out a surprise withdrawal from two prominent military bases in the eastern Deir ez-Zor countryside.”

The bases are the al-Omar field - the largest American base in Syria- and the Conoco gas plant, which are currently under the control of the Kurdish-led Syrian Democratic Forces (SDF).

“The withdrawal began gradually on May 18 before accelerating over the past two days. US convoys, including armored vehicles and logistical equipment, were seen leaving their positions… amid increased overflights by the international coalition,” Abdulrahman added, noting that SDF commandos have been deployed to the evacuated positions.

The bases had been frequently targeted by Iran-backed armed groups over the past two years.

The United States alongside the international coalition played an important role in defeating the Islamic State (ISIS) in Syria in cooperation with the SDF, and have been a key ally of the SDF throughout the war against ISIS and later. Washington brokered a truce deal between Turkey-backed forces and the SDF earlier in 2025.

US forces still maintain a position in the Shaddadi base south of Hasakah, where Washington and the global coalition will continue to engage in military cooperation with the SDF during security campaigns targeting ISIS remnants, according to Abdulrahman.

The withdrawal has sparked concern of a power vacuum forming after one of the biggest military movements of the US in northeastern Syria, Abdulrahman said, especially at a time of fragile security and mounting challenges.

The US suspended diplomatic relations with Syria in 2012 in light of the country’s civil war, but has begun working with the new Damascus government in recent months after the fall of the Bashar al-Assad regime.