A pair of U.S. Air Force F-15E Strike Eagles fly over northern Iraq after conducting airstrikes in Syria on September 23, 2014.

U.S.-led coalition jets reportedly struck Syrian and allied forces inside Syria, the coalition said Thursday.

May 18 #Coalition struck #Syrian pro-regime forces advancing in a de-confliction zone near At Tanf posing a threat to #US partner forces1/3 — Inherent Resolve (@CJTFOIR) May 18, 2017





This was despite #Russian attempts to dissuade pro-regime movement towards At Tanf, #Coalition aircraft show of force, & warning shots2/3 — Inherent Resolve (@CJTFOIR) May 18, 2017





The area, which is near Syria’s border with Jordan and Iraq, is where U.S. and U.K. special-operations forces train Syrian rebels.

BuzzFeed News cited a U.S. defense official as confirming the strike was launched by the U.S. That would mark the first time the Syrian regime has been directly targeted by the U.S. since President Trump ordered a missile strike last month in response to the Assad regime’s use of chemical weapons—and they also mark an escalation in the U.S. involvement in the Syrian civil war.

CBS News reported that the strikes were in response to Syrian regime vehicles violating a deconfliction zone set up around the military base in al-Tanf. It said Assad’s regime had violated the zone twice in recent days. Here’s more:

In one incident, 27 regime vehicles drove within 18 miles of al-Tanf, which breached the 34 mile radius of the army convoy. U.S. aircraft attempted to buzz the regime, but when the convoy didn't turn around, they conducted a strike against some of the vehicles. In the second incident, an unarmed Syrian SU-22 fighter-bomber entered the deconfliction zone and was intercepted by a pair of F-22 fighter aircraft.

Fars, the Iranian news agency that is allied with Iran’s Islamic Revolutionary Guard Corps, reported that 3,000 fighters from Hezbollah, the Iran-backed Lebanese Shia militia, were deployed to Tanf “to prepare the Syrian army and its allies for thwarting the U.S. plots in the region and establish security at the Palmyra-Baghdad road.” It said the Syrian military and others had also been sent to the region.