WASHINGTON/SEOUL -- The U.S. and North Korea are trying to maintain momentum for disarmament negotiations after a second summit that only underscored their rift over what denuclearization means.
Both sides have given largely positive accounts of last week's two-day meeting between U.S. President Donald Trump and North Korean leader Kim Jong Un in Hanoi.
But further progress hinges on whether Washington and Pyongyang can reach common ground on what it means to have a nuclear-free Korean Peninsula. At the summit, Trump made an attempt to define in writing the terms of a deal that would include eliminating North Korea's stockpiles of chemical and biological weapons.
The meeting's focus "was whether North Korea was prepared to accept what the president called 'the big deal,' which is denuclearize entirely under a definition the president handed to Kim Jong Un and have the potential for an enormous economic future," U.S. National Security Adviser John Bolton told American broadcaster CBS in interview aired Sunday.
Bolton did not say what Trump's definition of denuclearization entails. But past comments from American officials suggest that this includes eliminating all North Korean nuclear facilities, as well as warheads and missiles.
"If North Korea commits to complete denuclearization, including its ballistic missile program and its chemical and biological weapons programs, the prospect of economic progress is there," Bolton said.
But in Hanoi, Kim offered only to dismantle the Yongbyon nuclear complex in exchange for lifting of five of 11 rounds of sanctions imposed on the country by the United Nations Security Council -- those not directly tied to Pyongyang's weapons programs.
"This is the biggest denuclearization step we can take based on the current level of trust between the two countries," Foreign Minister Ri Yong Ho said last week. But for the U.S., the North Korean demand was nearly tantamount to a full rollback.
This is not the first time that the countries have clashed on what denuclearization means. North Korea previously called on the U.S. to stop extending its nuclear umbrella over allies Japan and South Korea.
For now, the two sides seem to be trying to keep dialogue alive. The U.S. and South Korea inaugurated on Monday a new joint military exercise called Dong Maeng, from the Korean term for "alliance," that is smaller in scale from past spring drills that North Korea denounced as preparations for war.
It will last until March 12, about half the length of similar drills in the past.
The decision to stop the allies' joint Foal Eagle and Key Resolve field exercises reflected "our desire to reduce tension and support our diplomatic efforts to achieve complete denuclearization of the Korean Peninsula," the Pentagon said in a news release.
North Korean media are also reporting mainly the positive aspects of the Trump-Kim summit. The leaders "agreed to keep in close touch with each other for the denuclearization of the Korean Peninsula and the epochal development" of bilateral relations in the future, the official Korean Central News Agency reported Friday.
Bolton gave no hard deadline for negotiations. Trump "kept the door open" from the first summit in Singapore eight months earlier to the Hanoi meeting, and "the North Koreans can walk through it -- it's really up to them," Bolton said. "That's the diplomatic window."
Meanwhile, Kim said in "our last meeting" that "we're going to go through many stations ... before we achieve this deal," Bolton said. "The meeting in Hanoi was one such station."
The North Korean leader departed from Vietnam by train on Saturday to arrive home as early as Tuesday morning. There was speculation that he could stop in Beijing on the way to meet with Chinese President Xi Jinping, but he was expected to go straight back to plan out his next steps.