The U.S.-led anti-Daesh coalition said Tuesday it struck forces allied to Syrian President Bashar al-Assad after they advanced on an area where the U.S. is training partner forces.
The strikes were carried out after a convoy that included "a tank, artillery, anti-aircraft weapons, armed technical vehicles and more than 60 soldiers" ignored repeated warnings, the coalition said.
The forces posed a threat to coalition and allied forces based at a garrison in the southeastern Syrian border town of at-Tanf as they violated what the coalition called a "well-established de-confliction zone".
Two artillery pieces, and an anti-aircraft weapon were destroyed, and a tank was damaged, according to the coalition.
The coalition previously struck pro-regime forces on May 18 under circumstances that it described similarly to what it said unfolded on Tuesday.
The coalition said it does not seek confrontation with the "Syrian regime or pro-regime forces", but stressed it is ready to defend its troops and partners "if pro-regime forces refuse to vacate the de-confliction zone.
"The Coalition calls on all parties in southern Syria to focus their efforts on the defeat of ISIS, which is our common enemy and the greatest threat to regional and worldwide peace and security," the coalition added in a statement, referring to the Islamic State of Iraq and Syria, another name for Daesh.
The clash comes as U.S.-backed groups launch a long-anticipated offensive to oust Daesh from its de facto Syrian capital further north in Raqqah.