A force supporting Syrian President Bashar al-Assad attacked a base last week in Syria held by a U.S.-backed coalition, prompting a lethal response that the Pentagon said killed around 100 of the attackers and injured 200-300 more.
Air Force Lt. Gen. Jeffrey L. Harrigian briefed Pentagon reporters on Tuesday from the combined air operation center at Al Udeid Air Base base in Qatar. The commander of U.S. Air Forces Central Command said he was not going to speculate on the composition of the group that carried out the attack against U.S.-backed forces. Bloomberg reported the attacking force was primarily composed of Russian mercenaries and that about 200 were killed, but the Defense Department would only describe the attackers as "pro-regime" in reference to the Syrian regime.
The U.S.-backed coalition in Syria, which includes the Syrian Democratic Forces (SDF), has been focused on eliminating the Islamic State's presence. The forces supporting the Assad government have also fought against the Islamic State in Syria. However, the pro-regime forces have recently competed with the Kurdish-led SDF in eastern Syria to seize territory rich in oil and natural gas, the New York Times reported.
Harrigian gave a timeline of events in which the pro-regime force had to retreat after it attacked an "established SDF position" where some U.S. personnel were embedded.
"On the evening of February 7, the coalition acted in self-defense where coalition advisers were present to support SDF from a hostile force launching an unprovoked coordinated attack across the Euphrates river against an established SDF position," Harrigian said. "The hostile force initiated the attack by firing artillery and tank rounds at the SDF position, followed by a battalion-sized dismounted formation, attempting to advance on partner forces under cover of supporting fires from artillery, tanks, and multiple launch rocket systems and mortars."
The air force general said the United States was in contact with Russia before carrying out the defensive strike.
"We immediately contacted the Russian officials on the deconfliction telephone line to alert them on the unprovoked attack," he said. "After these calls, coalition officials approved strikes to destroy hostile forces."
"Air Force joint terminal attack controllers (JTACs) embedded with the SDF called in precision strikes for more than three hours from aircraft and ground artillery, directing F-15Es, MQ-9s, B-52s, AC-130s, and AH-64 Apaches to release multiple precision-fire munitions and conduct strafing runs against the advancing aggressor force, stopping their advance and destroying multiple artillery pieces and tanks," he added.
Harrigian also explained the coalition force was prepared for the attack because it had intelligence on the attackers’ military buildup.
"Despite the attack being unprovoked, it was not entirely unexpected," he said. "The coalition observed a slow buildup of personnel and equipment the previous week, and we reminded Russian officials of the SDF and coalition presence via the telephone deconfliction line. This was well in advance of the enemy force’s attack."
Harrigian said he would "not speculate on the composition of the attacking force" or about whose command it was under. When asked by a reporter to further explain "pro-regime force," the general said it is one "encompassing a wide group of folks," but would not speculate further.
The general pressed the points that U.S. forces are focused on ISIS in Syria, they were not "looking for a fight," and the deadly strikes were ordered in self-defense.
"This is a hostile force that was coming after our partners and coalition advisers, and so we’re going to defend ourselves," he said. "I think as we work through the assessment right now, ‘pro-regime force’ is probably the best definition we have to describe who they were."