It's a major step in the fight to push ISIS out of the Syrian city of Raqqa. The U.N. says there are up to 100,000 civilians still trapped in the city.
Raqqa is the most important stronghold for the militant group in Syria and fell under its control in 2014. This offensive is expected to be difficult and is seen as pivotal in the fight against ISIS.
The strike was requested by America's partners "who had identified the target location as an ISIS fighting position," U.S. Central Command said Thursday.
The U.S. considers deploying hundreds more American troops to Syria in the final phase of the war against ISIS — one that could reshape borders and relationships in the Middle East.
The bombing, near a revered cemetery on the border of the old city of Damascus, appears to have targeted Shiite visitors from Iraq. There was no immediate claim of responsibility for the attack.
Two offensives in two countries are aimed at retaking Syria's Raqqa and Iraq's Mosul. Raqqa is the Islamic State's de facto capital, while Mosul is the group's most important stronghold in Iraq.