Two US personnel suffered minor injuries after an apparent rocket strike on a base in eastern Syria, US officials said on Thursday, an attack which a war monitor and a tribal source said was carried out by Iran-backed militias.
The US 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.
The officials said this was based on initial information and could change.
US forces have deployed into Syria during the campaign against ISIS, partnering with a Kurdish-led group called the Syrian Democratic Forces. Iran-backed militias have established a foothold in Syria while fighting in support of President Bashar al-Assad during the country's 11-year-long war.
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 US forces are based in Deir Ezzor 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.
The Syrian Observatory for Human Rights said rockets had been fired after midnight at the base from an area where Iran-backed militias exercise influence.
The Observatory said the US-led forces returned fire. Reuters could not independently verify the report.
The Observatory also reported that explosions were heard in the area before noon on Thursday.
US troops came under rocket fire in the same area last year, in apparent retaliation for US airstrikes against Iran-aligned militia in Syria and Iraq.
The militias are heavily concentrated west of the Euphrates in Deir Ezzor province, where they get supplies from Iraq through the al-Bukamal border crossing.
