The United States on Thursday launched air and missile strikes at Houthi rebel targets in Yemen after the Iran-backed militia staged multiple drone and missile attacks on ships traversing the Red Sea, according to a Defense Department official.

The strikes came after the Houthis ignored weeks of warnings by the U.S. and its allies to stop their attacks on vessels in the commercially important waterway. U.S. destroyers have shot down dozens of drones and missiles that posed a threat to their sailors since November.