The United States and Britain on Friday began carrying out strikes against sites used by the Houthi rebel group in Yemen.
US officials said targets included logistical hubs, air defence systems and weapons storage locations. US media reported that the strikes involved fighter jets and Tomahawk missiles.
The Houthis control large swathes of western Yemen, including the capital, Sanaa.
US President Joe Biden said the strikes represented a "united and resolute" response to Houthi attacks on international ships and that the US would "not hesitate to direct further measures" against the militant group.
"The response of the international community to these reckless attacks has been united and resolute," he said in a statement released by the White House.
Biden said the US and UK strikes were carried out with support from Australia, Bahrain, Canada, and the Netherlands.
"These targeted strikes are a clear message that the United States and our partners will not tolerate attacks on our personnel or allow hostile actors to imperil freedom of navigation in one of the world’s most critical commercial routes," he said.