A U.S. attack on forces loyal to Syrian President Bashar Assad killed more than 100 in the country's north on Feb. 8, and the regime came roaring back with airstrikes of its own on rebel forces near Damascus.
The airstrikes from Assad killed 21 and injured 125, the Syrian Observatory for Human Rights reported on Feb. 8.
Assad's strikes followed what the U.S. called an "unprovoked attack" by his forces on the headquarters of the Syrian Democratic Forces (SDF), a group of anti-Assad fighters the U.S. has trained and supported for years.
The U.S. responded with artillery, tanks, and rocket fire.
Syrian Arab trainees await commands from an instructor at a Syrian Democratic Forces' rifle marksmanship range in Northern Syria, July 31, 2017. Small arms and ammunition represent the majority of support from Coalition Forces to the SDF, the most capable and reliable force in Syria currently making daily gains to reclaim Raqqah from the hold of ISIS. (U.S. Army photo by Sgt. Mitchell Ryan)
In the exchange, no U.S. forces were reported hurt or killed, but 500 of Assad's were said to be engaged, many wounded, and 100 dead.
"We suspect Syrian pro-regime forces were attempting to seize terrain SDF had liberated from Daesh in September 2017," a U.S. military official told Reuters.
The pro-Assad forces were "likely seeking to seize oilfields in Khusham that had been a major source of revenue for [ISIS] from 2014 to 2017."
But Syrian state media characterized the event differently, saying the U.S. had bombed "popular local forces fighting" ISIS, and that it was a U.S. "attempt to support terrorism." The Assad regime and its Russian backers have an established history of calling anyone who doesn't support the regime a terrorist.
Though some of the anti-Assad resistance has become entwined with Islamist groups like al-Qaeda, the U.S. vets the groups it works with and maintains that the SDF are moderate rebels who were instrumental in the defeat of ISIS.
Syria wants the U.S. out, but it won't go without a fight
Syria's air offensive on rebel-held areas near Damascus has been going on for days, with local reports claiming that airstrikes from the Syrian government and Russia killed scores of civilians.
Activists and first responders said that at least 55 people were killed after the airstrikes on Feb. 6.
Syria has seen a dramatic uptick in air raids by Russian and Syrian jets after a Russian jet was downed by Syrian rebels using a portable anti-air missile system.
Though Russia announced its forces would withdraw from Syria in December 2017, the recent rash of renewed strikes shows they have stayed put, and are likely responding to an increased need to support the Assad regime.
In January 2018, Syria vowed that it would eject U.S. troops from the country, but since then the U.S. announced plans to stay there long enough to counter Iran's growing influence.
Meanwhile, the U.S. began a more vocal campaign of accusing Syria and Russia of using chemical weapons in the conflict.
The U.S. has repeatedly flirted with the idea of carrying out another punitive strike against the Assad regime as reports of gas attacks grow more numerous.