Lieutenant General Jeffrey Harrigian, commander, U.S. Air Forces Central Command, provided more details on the February 7 strikes on Syrian government forces in the province of Deir Ezzor during the February 13 press briefing of the Department Of Defense (source):
For a quick recap, on the evening of February 7th, 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.
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.
At the start of these — of this attack, coalition aircraft, including F-22s and MQ-9s, were overhead providing protective overwatch, defensive counter-air, and ISR support — as we have done daily throughout the defeat — the fight to defeat ISIS.
We immediately contacted the Russian officials on the deconfliction telephone line to alert them to the unprovoked attack on a known SDF and coalition position. After these calls, coalition officials approved strikes to destroy hostile forces.
On the ground, Air Force joint terminal attack controllers 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.
As the hostile forces turned west and retreated, we ceased fire.
Despite the attack being unprovoked, it was not entirely unexpected. 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 forces’ attack.
I know you’re going to ask, so I’m going to be clear that I will not speculate on the composition of this force or whose control they were under. As I’ve said throughout my nearly two years commanding coalition air forces, we are focused on a singular enemy: ISIS. We’re not looking for a fight with anyone else, but as Secretary Mattis said last week, “If you threaten us, it will be your longest and worst day.”