NEW YORK — North Korea’s leader is “begging for war,” the U.S. ambassador said Monday at an emergency meeting of the U.N. Security Council, as members called for punishing the country with even stronger sanctions for its powerful nuclear test. Ambassador Nikki Haley said the U.S. would look at countries doing business with the North — which include China — and planned to circulate a resolution this week with the goal of getting it approved Sept.