In Yemen, the U.S.-backed, Saudi-led coalition said Tuesday it had shot down a missile fired by rebels and aimed at the heart of the Saudi kingdom. Video posted by Houthi militants showed the launch of the short-range ballistic missile, which the rebels said was aimed at the royal palace in Riyadh. Saudi officials immediately blamed Iran for supplying the missile—a charge denied by both Tehran and the Houthi rebels. The escalating tensions came as the U.N.’s top human rights official said U.S.-backed, Saudi-led coalition airstrikes have killed at least 136 civilians and noncombatants in the past two weeks alone, including seven airstrikes on a prison that killed 45 people and an assault on a farmhouse that killed 14 children and six adults.