White House press secretary Jay Carney called the comments "needlessly provocative."
In its latest invective against the U.N. Security Council's unanimously-approved resolution Tuesday calling for tightened sanctions for its Dec. 12 rocket launch, North Korea directed its ire at the United States, but didn't say when the tests would be conducted.
The isolated communist country's National Defense Commission in a statement against the resolution, carried by the official Korean Central News Agency, said:
"We do not hide that a variety of satellites and long-range rockets will be launched and a nuclear test of higher level will be carried out in the upcoming new phase of the anti-U.S. struggle, targeting against the U.S., the sworn enemy of the Korean people."
China's official Xinhua News Agency quoted the North Korean commission as declaring there will "no longer exist the six-party talks and the Sept. 19 joint statement," as "the U.N. Security Council has been reduced into an organization bereft of impartiality and balance."
"North Korea's statement is needlessly provocative, and a test would be a significant violation of United Nations Security Council resolutions," Carney said. "Further provocations would only increase Pyongyang's isolation, and its continued focus on its nuclear and missile program is doing nothing to help the North Korean people.
Separately, South Korea's Yonhap News, citing a South Korean intelligence source, said North Korea has completed all technical preparations for a nuclear test, which would be its third after similar tests in 2006 and 2009. The source said the country needs only a few days' notice to carry it out once the country's leadership makes a decision.
Since the Dec. 12 rocket launch, there have been reports North Korea may be preparing for its third nuclear test.
Tuesday's U.N. Security Council resolution, which was approved unanimously, would tighten and expand existing sanctions against the North for its Dec. 12 rocket launch. Those sanctions were imposed after North Korea conducted missile tests followed by its two nuclear tests in 2006 and 2009.