WASHINGTON (Reuters) - The U.S. State Department said on Monday the United States took North Korean threats to use nuclear weapons seriously and urged Pyongyang to halt its provocations, including testing nuclear devices and long-range rockets. North Korean leader Kim Jong Un ordered his country last week to be prepared to use nuclear weapons at any time and to be ready to carry out a pre-emptive attack, state media reported. His comments came as U.S. and South Korean forces conducted annual military exercises amid heightened tensions on the peninsula following the North’s recent nuclear and missile tests, which prompted the United Nations to impose new sanctions on Pyongyang. “We certainly do take those kinds of threats seriously ... and again call on Pyongyang to cease with the provocative rhetoric, cease with the threats and quite frankly, more critically, cease with the provocative behavior, the actual conduct, that has led to yet another round of international sanctions,” State Department spokesman John Kirby said. 