The U.S. coalition said in a statement Saturday that four soldiers were wounded in a rocket attack on a base in eastern Syria where US troops are stationed.
The attack took place at 01:05 local time on Thursday, during which two rockets hit a base rocket in eastern Syria, the statement said.
According to the Rai Al-Youm news website, the statement also said that four American soldiers were wounded and suffered brain damage in the rocket attack on the base.
Pentagon spokesman John Kirby told a news conference that they had no idea which side or group had carried out the attack.
Earlier, US sources said two US soldiers had been wounded in the attack.