Saudi Arabia bombed the port city of Mukalla in Yemen on Tuesday over what it described as a shipment of weapons for a separatist force there that arrived from the United Arab Emirates. The UAE did not immediately acknowledge the strike. The attack signals a new escalation in tensions between the kingdom and the separatist forces of the Southern Transitional Council, which is backed by the Emirates. It also further strains ties between Riyadh and Abu Dhabi, which had been backing competing sides...