North Korea is threatening to attack South Korea if it adopts the U.N.'s newly tightened sanctions — a move it says would be tantamount to "a declaration of war" by its southern neighbor. "If the puppet group of traitors takes a direct part in the U.N. 'sanctions,' [North Korea] will take strong physical counter-measures against it," it said. That threat was just the latest bluster from the reclusive Communist country, whose bellicose anti-Western screeds regularly achieve a sort of poetry. The country lashed out Thursday at the U.S., which it called its "sworn enemy," and vowed to conduct more rocket launches and nuclear tests, just after the U.N. Security Council condemned its December rocket launch and expanded sanctions in response. (North Korea says that launch was a peaceful satellite mission, but it is widely believed to have been a test of long-range missile technology.) After the U.N. announced its new sanctions, the U.S. added additional ones, too. Seoul has said that for its part it will follow the U.N.'s lead for now.