In what has amounted to the most intense fighting in eastern Syria in almost a year, US-backed opposition forces attacked three posts manned by pro-government forces in the strategically important Deir Ezzor province on Monday.
The Arab-led Deir Ezzor Military Council, a faction of the US-aligned Kurdish-led Syrian Democratic Forces (SDF), publicly confirmed the assault, claiming to have killed 18 enemy fighters in response to the shelling of the villages of Dahla and Jdaidet Bakkara last week, which killed at least 11 civilians.
In a statement, opposition forces claimed that the attack targeted the shelling's origin.
An opposition war monitor based in Britain, the Syrian Observatory for Human Rights, confirmed the deaths of at least nine pro-government fighters.
The escalation of violence over the days prior to the assault saw clashes between the SDF and Syrian government-aligned forces that left more than a dozen people dead and came amid mounting concerns about a wider regional conflict following the killings of senior leaders in both Gaza-based Hamas and Lebanon's Hezbollah.
Assad reclaims Syria’s territory with Russian, Iranian aid
Syrian dictator Bashar al-Assad's government, which had nearly collapsed at one point during the country’s ongoing civil war, has since reclaimed control over most Syrian territory thanks to intervention from allies Russia and Iran.
The SDF has partially controlled the Euphrates River-intersected Deir Ezzor province since 2017. Since 2015, the US has also stationed troops in the area as part of a mission to combat the Islamic State group.
The SDF and US forces control the west bank of the river and the valuable oilfields located there, while pro-government fighters hold sway over the east bank, providing Iran with a critical land corridor to reach the Mediterranean.