The U.S. military carried out at least one strike in self defense in Syria's Deir al-Zor region overnight, a U.S. official said Tuesday, adding it was unrelated to the ongoing rebel advances in the country.
The official, speaking on the condition of anonymity, did not say specifically whom the strike targeted.
The United States has a small number of troops at a base in a gas field in the Deir al-Zor province and has occasionally carried out strikes in the region, including against Iran-backed forces. The region also has a presence of Islamic State militants, who U.S. troops have been fighting since 2014.