When John Kerry was selected as U.S. Secretary of State, Korea watchers wondered which policy path he'd follow. Would he continue his predecessor Hillary Clinton's role as the backbone of the Obama administration, pushing for a firm policy toward the Kim regime? Or would he maintain his long-held advocacy for negotiations, even if it meant lowering the bar of Pyongyang's compliance?

Secretary Kerry's first trip to Asia, which ended this Sunday, provided the answer. He showed greater eagerness to negotiate with Pyongyang than to support allies threatened with attack. Rather than identifying North Korean belligerence as the most likely catalyst for a military clash, Mr. Kerry instead asserted in Seoul that the greatest danger was "for a mistake [that] inadvertently gets out of control."

In a Beijing press conference, Mr. Kerry suggested that the U.S. could remove some newly fortified missile defenses in exchange for progress on talks. In doing so, he offered his country's antimissile capability in Asia as a bargaining chip even before North Korea thought of demanding it. The offer was also a sop to China, which feels threatened by a U.S. military buildup in Asia, a strategy partly intended to reassure victims of Beijing's regional bullying.

Mr. Kerry's diplomatic approach to the Korean peninsula is based on two faulty premises. First, that North Korea is willing to negotiate away its nuclear weapons. Secondly, that China will alter its own longstanding resistance to pressuring Pyongyang.

For years, North Korea has unambiguously declared it would never abandon its nuclear arsenal. Pyongyang even revised its constitution in May 2012 to enshrine itself as a "nuclear armed nation." The Central Committee of the Korea Workers Party Central, the country's highest governing body, formally resolved last month that "possession of nuclear weapons shall be fixed by law [and are not] a political bargaining chip."

Mr. Kerry is nevertheless hopeful that Beijing has become exasperated enough to turn the screws on its ally. This seems unlikely. During the most recent United Nations deliberations on North Korea, Beijing remained obstructionist against comprehensive and effective sanctions. And when the deputy editor of an influential Communist Party journal wrote an article critical of North Korea in late February, he was fired.

Contrary to Mr. Kerry's claims after meetings in Beijing last weekend, there has been nothing in Chinese statements to suggest a willingness to increase pressure on North Korea. After meetings with Mr. Kerry, Chinese officials merely committed to stressing peaceful resolution through dialogue. Beijing never singled out North Korea for criticism, instead continuing its bland entreaties for "all countries" to show restraint and return to the six-party talks.

Equally important during Mr. Kerry's trip was what he didn't say. In Tokyo, his Japanese foreign minister counterpart emphasized that for dialogue to occur, North Korea must first honor its commitments, immediately stop its provocative behavior and take actions to prove it has changed its ways. Mr. Kerry instead repeated his desire to revive the moribund Six Party Talks.

One fear is that Mr. Kerry's remarks reflect a broader policy reversal, suggesting that the U.S. will yield to North Korean bluster. Mr. Kerry said in Seoul that President Obama had cancelled a number of military exercises and significantly lowered U.S. rhetoric over the past week. Also disquieting is the possibility that Mr. Kerry is going his own way in a dysfunctional administration. In confirmation hearings Mr. Kerry signaled he was unconvinced of the need for an increased military ramp-up in the Pacific, which is the basis of President Obama's strategic pivot to Asia.

What's known is that rather than standing up to North Korean belligerence, Mr. Kerry stepped back. Speaking in Seoul of his desire to "find a way for reasonableness to prevail" through negotiations, he said: "Let's face it. Everyone here knows this, we've got enough problems to deal with around the world." One can only imagine the glee in Pyongyang and the trepidation in Seoul for Mr. Kerry to prioritize other regions over defending the U.S.'s Korean ally. So much for the Asian pivot.

-Mr. Klingner is senior research fellow at the Heritage Foundation and previously served as the U.S. Central Intelligence Agency's deputy division chief for Korea.