By Nandita Bose and Mohammed Ghobari WASHINGTON/ADEN (Reuters) – President Joe Biden vowed further military action against Yemen’s Houthi forces if they keep up their attacks on shipping in the Red Sea despite dozens of U.S. and British air strikes on the Iran-backed group’s facilities. Intensifying concerns about a widening regional conflict, U.S. and British warplanes, ships and submarines this week launched missiles against targets across Yemen controlled by the group, which has cast its maritime campaign as support for Palestinians under siege by Israel in Hamas-ruled Gaza. Even as Houthi …