A U.S.-led coalition launched more than a dozen strikes on Houthi rebel targets in Yemen late Thursday, officials said, two days after the Yemeni rebel force defied an ultimatum to halt its attacks on ships transiting the Red Sea with a barrage of missiles and drones.

The strikes, which were conducted by U.S. and British forces and supported by Australia, Bahrain, Canada and the Netherlands, were intended to reduce the Houthis’ campaign, which the Iran-backed rebel group said it launched in response to Israel’s war on the Hamas militant group in Gaza.