Two U.S. military personnel suffered minor injuries after an apparent rocket attack on an American military base in eastern Syria, U.S. officials said Thursday.
The officials, speaking on the condition of anonymity, said one of the personnel had already been treated and released while the second was being checked for traumatic brain injury after the incident, clarifying this was based on initial information and could change.
While the attack was not claimed by any group, a tribal source in the area said several rockets were fired by an Iran-backed militia, and two landed in the area of al-Omar oil field where U.S. forces are based in Deir al-Zor province, near the Iraqi border.
The rockets were launched from an area west of the Euphrates River, where Iran-backed militias have a presence, the source said, which The Syrian Observatory for Human Rights said fired after midnight.
The Observatory, a UK-based organisation that reports on the war in Syria using what it describes as sources on all sides of the conflict, said the U.S.-led forces returned fire, adding that explosions were heard in the area before noon on Thursday.
U.S. troops came under rocket fire in the same area last year, in apparent retaliation for U.S. air strikes against Iran-aligned militia in Syria and Iraq.
Iran-backed forces have targeted U.S. forces in Iraq and Syria in the past, most recently in January. Last month, Tehran took direct responsibility for a rocket attack in Iraqi Kurdistan on U.S. targets, a rare publicly declared assault bypassing proxy groups.
Syria's main oilfields are in areas controlled by U.S.-backed forces and their proceeds are a major source of financing for the Syrian Democratic Forces, a Kurdish-led force operating autonomously in most of Syria's northeast.
Iranian-backed militias are heavily concentrated west of the Euphrates River in Deir al-Zor province, where they get supplies from Iraq through the al-Bukamal border crossing.