Two rockets targeted a US patrol base in northeastern Syria late Friday, the third such attack in nine days, US Central Command said.
Centcom did not indicate who fired the rockets but said, in a statement, that they aimed at "coalition forces at the US patrol base in Al-Shaddadi, Syria".
The strike at about 10:30 pm (1930 GMT) caused no injuries or damage to the base or coalition property, said Centcom, which covers the Middle East region.
The US troops support Syrian Democratic Forces (SDF), which are the Kurds' de facto army in the area and led the battle that dislodged the Islamic State group (IS) from the last scraps of their Syrian territory in 2019.
Hundreds of American troops are still in Syria as part of the fight against IS remnants.
"Syrian Democratic Forces visited the rocket origin site and found a third unfired rocket," Centcom added in its latest statement.
On November 17 rockets targeted the coalition's Green Village base which is in Syria's largest oil field, Al-Omar, near the Iraqi border, Centcom said at the time. There were no injuries.
A war monitor, the British-based Syrian Observatory for Human Rights which has a wide network of sources in Syria, said that strike came from "a base of pro-Iranian militias".
Such groups have significant influence in the Syria-Iraq border region.
