President Joe Biden said on Saturday the United States had delivered a private message to Iran about Iran-backed Houthis responsible for attacking commercial shipping in the Red Sea. "We delivered it privately and we're confident we're well-prepared," Biden told reporters at the White House before departing to the Camp David presidential retreat for the weekend. The latest strike, which the US said hit a radar site, came a day after dozens of American and British strikes on Houthi facilities in Yemen.