Twenty-two US service members were injured in a helicopter “mishap” in north-east Syria on Sunday, the US military said late on Monday, without disclosing the cause of the incident or detailing the severity of the injuries.
The military’s Central Command said 10 service members had been evacuated to higher-level care facilities outside the region.
Central Command, which oversees US troops in the Middle East, said no enemy fire had been reported but added that the cause of the incident was under investigation. Officials at Central Command did not immediately respond to requests for further information.
The US-backed Syrian Democratic Forces (SDF), which control swathes of north-east Syria, referred questions to the US-led coalition under which American troops are deployed in the zone.
The autonomous Kurdish-led administration that governs the area and the central Syrian government in Damascus did not immediately respond to requests for comment.
There are about 900 US personnel deployed to Syria, most of them in the east, as part of a mission fighting the remnants of Islamic State. American troops there have come under repeated attacks in recent years by Iran-backed militia.
In March, 25 US troops were wounded in strikes and counter-strikes in Syria, which also killed one American contractor and injured another.
US forces first deployed into Syria during the Obama administration’s campaign against IS, partnering with the Kurdish-led SDF.
While IS is a shadow of the group that ruled over a third of Syria and Iraq in a caliphate declared in 2014, hundreds of fighters are still camped in desolate areas where neither the US-led coalition nor the Syrian army, with support from Russia and Iranian-backed militias, exert full control.
Thousands of other IS fighters are in detention facilities guarded by the SDF, the US’s key ally in the country.