The US and UK air strikes Thursday and Friday against sites in Yemen controlled by the Houthi militia damaged or destroyed about 90% of the targets struck, but the group retained about three-quarters of its ability to fire missiles and drones at ships transiting the Red Sea, two US officials said Saturday. The damage estimates are the first detailed assessments of the strikes by American and British attack planes and warships against nearly 30 locations in Yemen, and they reveal the serious challenges facing the Biden administration and its allies as they seek to deter the Iran-backed Houthis from retaliating.