WASHINGTON (AP) — The U.S. and Britain struck 18 Houthi targets in Yemen on Saturday, answering a recent surge in attacks by the Iran-backed militia group on ships in the Red Sea and Gulf of Aden, including a missile strike this past week that set fire to a cargo vessel.

According to U.S. officials, American and British fighter jets hit sites in eight locations, targeting missiles, launchers, rockets, drones and air defense systems. The officials spoke on condition of anonymity in order to provide early details of an ongoing military operation.