Twenty-one pro-Turkey fighters were killed on Wednesday during an attack on a Kurdish-held position near the Tishreen Dam, despite a US-brokered ceasefire extension in the region, according to the Syrian Observatory for Human Rights.

The attack, which was repelled by the Manbij Military Council, a unit of the Kurdish-led Syrian Democratic Forces (SDF), took place approximately 25 kilometers (15 miles) from the northern flashpoint town of Manbij. The Britain-based war monitor also reported casualties among the SDF and Manbij Military Council forces, though it did not provide specific figures.

According to the Observatory, the assault was supported by Turkish reconnaissance aircraft and led to intense clashes involving medium and heavy weaponry. In a statement, the SDF confirmed that its forces had “successfully repelled” the attackers and had launched a combing operation in the Tishreen Dam area to secure the position.

The clashes occurred just a week after Islamist-led rebels toppled Syria’s longtime leader, Bashar al-Assad, adding to the growing instability in the region. Tensions between US-backed Kurdish-led forces and Turkish-supported factions have remained high, despite ongoing diplomatic efforts.

On Tuesday, the United States announced an extension of the fragile ceasefire in Manbij, with attempts to negotiate a broader agreement with Turkey. However, the latest violence highlights the complexities of maintaining stability in northern Syria, where shifting alliances and unresolved disputes continue to fuel conflict.

The incident underscores the ongoing volatility in the region and raises concerns over the sustainability of the US-brokered ceasefire. Efforts to de-escalate tensions between Kurdish forces and Turkey-backed groups remain a critical component of international diplomatic efforts to stabilize Syria’s northern territories.