The United States and Britain called on Sunday for an immediate and unconditional ceasefire in Yemen to end violence between Iran-backed Houthis and the government, which is supported by Gulf states. On Saturday, a U.S. admiral said a destroyer had again been targeted in the Red Sea in an apparent failed missile attack launched from the coast of Yemen. "This is the time to implement a ceasefire unconditionally and then move to the negotiating table. We cannot emphasize enough today the urgency of ending the violence in Yemen,"," Kerry told reporters.