The Cutting Edge

"Now is a moment when I think all parties in the six-party process, in particular here, North Korea, should turn their attention to how to peacefully and diplomatically address challenges that concern them," U.S. envoy Glyn Davies said from Beijing.The U.N. Security Council on Wednesday unanimously condemned a North Korean rocket launch in December as a violation of existing sanctions that ban it from developing missile and nuclear technology. ​​North Korea responded Thursday by saying it would conduct a third nuclear test and carry out more rocket launches.

U.S. Defense Secretary Leon Panetta said he has seen no outward sign that North Korea will follow through soon on its plan to conduct a test. But that doesn't mean preparations aren't taking place. "They have the capability, frankly, to conduct these tests in a way that make it very difficult to determine whether or not they are doing it," Panetta said.

North Korea is estimated to have stored up enough weaponized plutonium for four to eight bombs, according to scientist Siegfried Hecker, who visited the North's Nyongbyon nuclear complex in 2010. In October, an unidentified spokesman at the National Defense Commission claimed that the U.S. mainland was within missile range. And at a military parade last April, North Korea showed off what appeared to be an intercontinental ballistic missile. White House spokesman Jay Carney on Thursday said North Korea's aggressive stance is unnecessary and warned against any further testing.

"North Korea's statement is needlessly provocative and a test would be a significant violation of United Nations Security Council resolutions," he said.