The top U.S. general overseeing a deployment of more than 5,200 troops to the border with Mexico said on Tuesday that troop levels would rise further, but declined to say how high or estimate what the operation will cost. Many basic questions remained unanswered a day after the Pentagon announced the open-ended deployment of over 5,200 active-duty troops to the border, including the scope of the mission as well as the Pentagon’s assessment of any threat posed by arriving migrants. […] General Terrence O’Shaughnessy, the head of U.S. Northern Command, defended the operation at a briefing on Tuesday. He echoed...