“Up to a handful” of militants were killed in the strikes, a US official told CNN.

The strikes, which mark the US military’s first known action under President Joe Biden, swiftly drew criticism from Democratic lawmakers. The site was not specifically tied to the rocket attacks, but Secretary of Defense Lloyd Austin said he was “confident” it was used by the same Iranian-backed Shia militias targeting US and coalition forces in Iraq with rocket attacks.

Pentagon spokesman John Kirby said the strikes took place “at President Biden’s direction” and were authorized not just to respond to the recent attacks against American and coalition forces but also to deal with “ongoing threats to those personnel.”

“Specifically, the strikes destroyed multiple facilities located at a border control point used by a number of Iranian-backed militant groups, including Kata’ib Hezbollah and Kata’ib Sayyid al Shuhada,” Kirby said. “The operation sends an unambiguous message; President Biden will act to protect American coalition personnel. At the same time, we have acted in a deliberate manner that aims to de-escalate the overall situation in both Eastern Syria and Iraq.”