The United States will talk to North Korea, but only if the country gets serious about negotiating the end of its nuclear weapons program, Secretary of State John Kerry said Friday during a visit to South Korea, a key U.S. ally.
"North Korea will not be accepted as a nuclear power," Kerry said after arriving in Seoul.
His trip to South Korea -- part of an Asian swing that also includes North Korean ally China -- came a day after a Pentagon intelligence assessment surfaced suggesting North Korea may have developed the ability to fire a nuclear-tipped missile at its foes.
Disclosed first by a congressman at a hearing Thursday and then confirmed to CNN by the Defense Department, the Defense Intelligence Agency assessment is the clearest acknowledgment yet by the United States about potential advances in North Korea's nuclear program.
Despite weeks of bellicose rhetoric from Pyongyang threatening nuclear attacks on the United States, South Korea and their allies, U.S. officials have characterized the North's saber rattling as largely bluster.
U.S. officials think North Korea could test-launch a mobile ballistic missile at any time in what would be seen by the international community as a highly provocative move.
But a senior administration official said there's no indication that any such missiles are armed with nuclear material.
Still, the defense agency said it has "moderate confidence" that North Korea could fit a nuclear weapon on a ballistic missile and fire it. But agency analysts think such a missile's reliability would be low -- an apparent reference to its accuracy.
White House spokesman Jay Carney told reporters Friday that the North Korean government "has not demonstrated the capability to deploy a nuclear-armed missile."
And Kerry said Friday that it would be inaccurate to suggest that North Korea, which has conducted three underground nuclear weapons tests since 2006, can launch a nuclear-armed missile, despite the DIA assessment.
"But obviously they have conducted a nuclear test, so there's some kind of device, but that is very different from miniaturization and delivery and from tested delivery and other things," he said.
He said any launch by North Korea would be a "huge mistake."
"If Kim Jong Un decides to launch a missile, whether it's across the Sea of Japan or in some other direction, he will be choosing willfully to ignore the entire international community, his own obligations that he has accepted, and it will be a provocative and unwanted act that will raise people's temperature with respect to this issue," Kerry said.
South Korean Foreign Minister Yun Byung-se, speaking with Kerry at a Friday news conference, urged North Korea to open talks.
"We urge North Korea to cease its reckless behavior and to stop issuing threats," he said. "Instead, we urge North Korea to respond to our call for building trust on the Korean Peninsula through dialogue, and now it is time for North Korea to make that choice."
A joint statement issued by South Korea and the United States before Kerry's departure emphasized Washington's commitment to defending Seoul "in the wake of recent unacceptable provocations" by the North.
"The United States stands vigilantly by the Republic of Korea's side, and is prepared for and capable of defending and protecting itself and its allies," the statement read.
Kerry now plans to visit China and tell leaders there that Pyongyang, as one senior administration official said, is "putting China's own interests at risk."
Washington wants Beijing to "stop the money trail into North Korea" and to carry a strong message to the North that getting rid of nuclear weapons on the Korean Peninsula is China's goal, said the official and a senior State Department official.
Defense Intelligence Agency report
The surprising Defense Intelligence Agency assessment of North Korea's potential nuclear capabilities emerged during Thursday's House Armed Services Committee hearing.
At the hearing, Rep. Doug Lamborn, R-Colorado, read from a declassified version of the document in which the DIA expresses "moderate confidence the North currently has nuclear weapons capable of delivery by ballistic missiles, however, the reliability will be low."
As Kerry did Friday, top officials in Washington tried Thursday to downplay concerns about the report.
Pentagon spokesman George Little said that "it would be inaccurate to suggest that the North Korean regime has fully tested, developed or demonstrated the kinds of nuclear capabilities referenced" in the DIA study.
That stance was echoed by James R. Clapper, director of U.S. national intelligence, who said: "North Korea has not yet demonstrated the full range of capabilities necessary for a nuclear-armed missile."