COSTELLO: North Korea says it's threatening to launch a preemptive nuclear strike. It's all in response to the U.S. and South Korea staging joint military exercises. Tensions are already running high on the Korean Peninsula after the North is hit with some of the toughest U.N. sanctions in years. Jim Sciutto in Washington with more. Good morning, Jim.</s>JIM SCIUTTO, CNN CHIEF NATIONAL SECURITY CORRESPONDENT: Good morning, Carol. You hit on it right there. Two things are going on right now. The joint U.S.-South Korea military exercises, their annual. The North Korea views this as a provocation. They believe that the U.S. and South Korea are training in effect to invade North Korea and carry out regime change. So every year there was always an angry response. But in addition to that, you have these new U.N. sanctions which are particularly tough. They of course follow North Korea's nuclear test and its missile test, so the tensions with North Korea, although always high, they're particularly high now. The White House and others, they view these as provocative steps by North Korea and a big test here, too, is that China is growing increasingly alarmed as well. The question is, what's going to change North Korea's behavior going forward? They hope that these sanctions will be a punishment and will change North Korea's own calculations about building its nuclear program, building its missile program, but really, they've tried these steps in the past, Carol. It hasn't worked. There's real concern. And it extends now from Washington all the way to Beijing.</s>COSTELLO: All right. Jim Sciutto, reporting live from Washington. Thank you. Still to come in the NEWSROOM, Peyton Manning hanging up the helmet for good.
North Korea Threatens Preemptive Nuclear Strike