U.S. warplanes attacked a movement of Syrian regime-backed fighters who violated an established deconfliction zone in southern Syria, a Pentagon official told the Washington Examiner Thursday.
The strike took place near the al-Tanf border crossing, on Syria's southern border with Jordan and Iraq, where U.S. special operations forces have been training counter-Islamic State troops for months.
The forces are armed and equipped by the regime, but are not part of Syria President Bashar Assad's military.
The attack was described as a "dynamic" strike in response to an immediate threat on the ground, as opposed to a pre-planned strike, such as the Tomahawk missile attack on a Syrian air base last month.
"This was in response to a threat to our forces," the official told the Washington Examiner.
A statement from U.S. Central Command is expected shortly.
Three U.S.-backed Syrian fighters were killed at the al-Tanf border crossing last month. U.S. special operations forces were there are the time, but it's unclear whether Americans were in the area for this most recent operation.