BEIJING — The United States and China reacted sharply to the latest torrent of belligerent language from North Korea, which called the U.S. its "archenemy" and said it planned to conduct another nuclear test despite international sanctions.
Beijing called for renewed negotiations with North Korea, while Washington promised "additional steps" beyond the expanded sanctions adopted by the United Nations this week. The sanctions notably had the support of China, suggesting growing frustration with its longtime ally.
The two superpowers were reacting to a tirade issued Thursday by North Korea's National Defense Commission that was provocative even by Pyongyang standards.
Calling the United States the "archenemy of the Korean people," the commission said, "We are not disguising the fact that the various satellites and long-range rockets that we will fire and the high-level nuclear test we will carry out are targeted at the United States.
"Settling accounts with the U.S. needs to be done with force, not with words."
The statement was released by North Korea's state-run news service.
The confrontational stand damped hopes that North Korea might be following a more moderate course under its new 30-year-old leader, Kim Jong Un, who took over 13 months ago after the death of his father, Kim Jong Il.
In Washington, White House Press Secretary Jay Carney called the remarks from Pyongyang "needlessly provocative." He said the recent U.N. Security Council resolution freezing assets and banning travel by North Korean officials should send a "strong message of the international community's opposition to North Korea's provocations."
"The United States will be taking additional steps in that regard," he said. He declined to say what those actions might be.
Defense Secretary Leon E. Panetta said the United States was "very concerned" about North Korea's threats and "fully prepared ... to deal with any kind of provocation."
China took a surprising step Tuesday by voting in favor of the Security Council resolution. On Thursday, Xi Jinping, the new head of the Chinese Communist Party, was quoted in major state-run newspapers in China recommending the resumption of the six-nation talks on North Korea's nuclear program. The talks collapsed in 2008.
Impoverished but heavily armed North Korea already has conducted two nuclear tests, in 2006 and 2009. After a botched missile launch last spring, it successfully launched a multistage missile in December, putting a satellite in orbit. Some experts considered the launch to be, in effect, a test of the country's intercontinental ballistic missile technology, although others disagreed that a satellite launch could serve that purpose.
Analysts generally believe that North Korea is still many years from a workable weapon that could reach the United States, much less one armed with a nuclear warhead.
Former CIA analyst Sue Mi Terry, now a senior research scholar at Columbia University's Weatherhead East Asian Institute, said in an email that she was "pleasantly surprised" by Beijing's backing of the Security Council resolution. However, she also said she fully expected North Korea to follow through with its threat to conduct a third nuclear test.
"Why would it not?" she said. "North Korea wants to be recognized by the international community as a nuclear power. Conducting a third nuclear test would only further boost Kim Jong Un's credentials and prestige."
Experts inside and outside the U.S. intelligence community disagree about the extent of the threat from Pyongyang. North Korea has enough plutonium to produce four to eight rudimentary nuclear weapons, according to estimates by Stanford University nuclear scientist Siegfried Hecker, who visited the country's atomic facilities in 2010. But few experts believe North Korea is able to make a warhead small enough to fit on a missile, and opinions differ about the range and accuracy of its missiles.
"We take it very seriously," said an Obama administration official who would not be quoted by name because of the sensitivity of the matter. "Any time you have a combination of nuclear technology and missile technology, it's an enormous threat to global security, and we would not want to pooh-pooh it. That said, our entire missile defense is designed to stop an Iranian or North Korean missile."
Demick reported from Beijing and Dilanian from Washington.