US Defense Secretary Warns of North Korea Missile Threat to U.S.

Mr. Gates is a former director of the C.I.A., and his statement, officials said, reflected both a new assessment by American intelligence officials and his own concern that Washington had consistently underestimated the pace at which the North was developing nuclear and missile technologies.

It is unclear how recent the new assessment may be, but Mr. Gates’ remarks, made just an hour after he met with Hu Jintao, China’s president, may have been partly intended to convince China that the Obama administration no longer regards the North as a concern only in the region. The administration has increasingly put pressure on China to try to persuade North Korea, a longtime China ally, to give up its nuclear weapons program.

“The Chinese are always talking about their ‘core interests’ and threats they may have to respond to,” said one American official deeply involved in North Korea strategy. “They needed to hear that we have a few, too.”

In comments to reporters during a visit to Beijing, Mr. Gates said he was worried that within a relatively short time frame North Korea would simultaneously continue to develop nuclear weapons and intercontinental ballistic missiles. That combination, he said, had increased the need for pressure on North Korea, particularly if there is another provocation on South Korea by the North like the deadly shelling of a South Korean island in November.