The U.S. launched an airstrike on a facility in eastern Syria used by Iranian-backed militias, in retaliation for what has been a growing number of attacks on bases housing U.S. troops in the region for the past several weeks, the Pentagon said.

Wednesday’s strike by two U.S. F-15 fighter jets was on a weapons storage facility linked to Iran’s Revolutionary Guard.

“The President has no higher priority than the safety of U.S. personnel, and he directed today’s action to make clear that the United States will defend itself, its personnel, and its interests,” Defense Secretary Lloyd Austin said in a statement