An "ineffective" rocket attack on Monday was launched on US coalition forces taking part in the anti-ISIS mission in north-east Syria, US Central Command has said.
The attack was aimed at the US Mission Support Site Conoco in the early evening local time, and resulted in "no injuries or damage" to the base.
"One rocket struck in the vicinity of the coalition outpost and an additional rocket was found at the attack's point of origin," a Centcom statement said.
Centcom spokesman Col Joe Buccino told The National: "These attacks, along with the ISIS strike, make clear that the region remains dangerous and we have troops in harm’s way, but we must continue the fight against ISIS.
"These attacks place coalition forces and the civilian populace at risk and undermine the hard-earned stability of Syria and the region."
US-Iran tensions have escalated in Syria. Last month, a drone attack killed an American contractor at a US base in Hasakah governorate.
The killing drew US air strikes on Iranian-aligned militia in the nearby governorate of Deir Ezzor, sparking more retaliation.
American troops have been in Syria since 2015, in a counter-terrorism mission aimed at countering Iranian-backed militias and preventing the resurgence of ISIS, in partnership with the Kurdish-led Syrian Democratic Forces.
Despite being defeated in Syria in 2019, the terrorist group continues to wage a low-level insurgency across northern Iraq and Syria, and often attacks members of the SDF.
Last week, a US strike killed senior ISIS leader Khalid Aydd Ahmad Al Jabouri in Syria's north-west region.
Col Buccino did not confirm if Monday's attempted strike is related to the escalation with Iran, but told The National that Centcom did not believe it "is a retaliation for the ISIS leader or that this is in any way tied to the strike against ISIS".
The Defence Department recently had to defend the presence of about 900 US forces there to Congress, after far-right Representative Matt Gaetz introduced a war powers resolution to withdraw troops from the country.
Centcom chief Gen Michael Kurilla told the House armed services committee last month that ISIS would return to power in "one to two years" should Washington withdraw from its mission in Syria.