The United States on Thursday urged Yemen’s Houthi rebels to release all US Embassy local staffers that they had detained, following the death of one of them after seven months in captivity. The Iran-backed Houthis seized the headquarters of the US Embassy in the Yemeni capital of Sanaa last October. They detained dozens of former staffers, many of whom were later released but at least 11 remained in the rebels’ custody. Yemen, the Arab world’s poorest nation, has been fractured by a brutal civil war since 2014, when the Houthis seized Sanaa and much of northern Yemen, forcing the internationa…