A U.S. defense official told VOA Thursday pro-Syrian government forces were operating in an "established deconfliction zone" near al-Tanf border crossing when a coalition commander on the ground deemed the force a threat to his troops.
The coalition-backed troops used "shows of force and warning shots" to try to get the pro-Syrian government force to move out of the area, according to the official. The commander decided to call in an airstrike after warnings were not heeded by the pro-Syrian government force, he added.
Local media have reported the strikes caused casualties and destroyed a number of vehicles. It is unclear whether Russian troops were operating with the pro-Syrian government forces at the time of the attack.
The U.S. defense official told VOA "the strike was not a change in policy," but rather an instance of the commander on the ground calling for force protection.
Tensions in the area have escalated as Syrian government forces and U.S.-backed Syrian forces continue to advance closer to each other. Both forces have said they are trying to push Islamic State fighters out of the area.