(SANAA, Yemen) — A rebel airstrike hit a Yemeni military parade outside the southern port city of Aden on Thursday, killing several troops from the Saudi-led coalition, Yemeni officials said. The attack by the rebels, known as Houthis, comes as a blow to Yemen peace efforts after a cease-fire was signed for the key port city of Hodeida last month, and just a day after U.N.