"Settling accounts with the U.S. needs to be done with force, not with words, as it regards jungle law as the rule of its survival," the commission said.
It was a rare declaration by the powerful commission once led by late leader Kim Jong Il and now commanded by his son. The statement made clear Kim Jong Un's commitment to continue developing the country's nuclear and missile programs in defiance of the Security Council, even at risk of further international isolation.
North Korea's allusion to a "higher level" nuclear test most likely refers to a device made from highly enriched uranium, which is easier to miniaturize than the plutonium bombs it tested in 2006 and 2009, said Cheong Seong-chang, an analyst at the private Sejong Institute in South Korea. Experts say the North Koreans must conduct further tests of its atomic devices and master the technique for making them smaller before they can be mounted as nuclear warheads onto long-range missiles.
Shortly before the commission issued its declaration, U.S. envoy on North Korea Glyn Davies urged Pyongyang not to explode an atomic device.
"Whether North Korea tests or not, it's up to North Korea. We hope they don't do it. We call on them not to do it," he told reporters in Seoul after meeting with South Korean officials. "It will be a mistake and a missed opportunity if they were to do it."
Davies was in Seoul on a trip that includes his stops in China and Japan for talks on how to move forward on North Korea relations.
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. Further provocation 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."