Those meetings happened five years ago, but they took place at the very beginning stages of the nuclear strategy Kim is executing to such dramatic effect now. At the time, Kim Jong Un had just enshrined his byungjin policy, stating that the North intended to develop a nuclear arsenal as a shield behind which it could modernize its economy. North Korean officials explained in these private sessions that Kim had issued the new policy after concluding that his country needed more nuclear weapons to deter the United States. It wasn’t just that the North Koreans were concerned about escalating tensions in late 2012 and early 2013, as well as continuing flights of nuclear-capable U.S. bombers over the Korean peninsula. The North Koreans also felt Washington and Seoul thought they could bully the North during the leadership transition that had begun with the death of Kim Jong Il in December 2011. One North Korean official I spoke to then said “nuclear” equaled “survival.”

But other officials said that was only under “present circumstances,” and their approach could change if the tense relationship between the United States and North Korea improved. That might explain a puzzling move by the North in June 2013, when the the National Defense Commission—the top government body in Pyongyang chaired by Kim—issued an important new pronouncement that it was open to negotiations on denuclearization. The Obama administration dismissed it at the time as propaganda. But a senior North Korean diplomat told a member of the American delegation that he himself was surprised Pyongyang was speaking of denuclearization again—especially after it had taken the issue off the table not long before.

At the meetings I attended, North Korean officials were emphatic that the pronouncement came from Kim Jong Un himself, and that it reflected his commitment to improving relations with the United States. They emphasized repeatedly that denuclearization could be on the agenda of bilateral talks with the United States, or even multilateral discussions such as the Six Party Talks that had been adjourned in 2008. That position showed a welcome flexibility—it seemed to mean the denuclearization offer wasn’t just a ploy to divide the Americans from their allies by getting them alone in the negotiating room. But it was also a reflection of North Korean self-interest; a more sympathetic China in the room could counterbalance the Americans. The North Korean officials only had one condition: The United States should not set preconditions, such as requiring the North to stop nuclear and missile tests, for negotiations to take place. They said they were, however, willing to take such steps once talks resumed.

Nevertheless, the North Korean proposal was difficult for the United States government to swallow. The Obama administration felt burned by the collapse of the February 2012 “Leap Day Deal,” which Washington had hoped would stop nuclear and missile testing, but which was soon followed by a North Korean launch of a satellite into space with a long-range rocket. Throughout 2013, the Obama administration, with the help of President Xi Jinping of China, tried to quietly revive talks, but only if North Korea met preconditions that demonstrated it was, as administration officials often stated publicly, “sincere” about denuclearization. Because Pyongyang would not meet them, Chinese shuttle diplomacy failed. And Pyongyang’s view was never fully explored.