Yet Mr. Kim seemed dissatisfied with the pace of development, and in his New Year’s speech this year called for “a breakthrough” in “re-energizing” the economy. In April — just days before his first summit meeting with Mr. Moon — he declared that byungjin was over. In its place, he said, all efforts should go to “socialist economic construction.”

Since then, the-economy-as-priority has been regular fare in North Korea’s media and from propaganda organs. Mr. Kim spent the summer months visiting farms, factories and tourist resorts, often chastising cadres for failing to implement development projects fast enough. During recent festivities celebrating the country’s founding, the parade featured floats with economic slogans and no ICBMs. If the iconic image of Mr. Kim in 2017 shows him watching a missile test, the one for 2018 shows him inspecting a fish cannery.

But much of the international community, and Washington in particular, has been so fixated on North Korea’s nuclear capabilities that it hasn’t paid enough attention to Mr. Kim’s broader strategic intentions — or how to make progress on denuclearization by working with, rather than against, them.

Mr. Kim wants North Korea to become a normal East Asian economy, catch up with and integrate into the region, and it’s in everyone’s interest to help him do so.

For North Koreans, economic development would bring opportunities to feed their families and run businesses, trade and perhaps travel. As the economic and social chasm between North and South began to close, South Koreans could slowly envisage a time when reunification seems plausible. With the peace process on the Korean Peninsula moving forward, Americans — who already have enough to worry about — could remove the threat of a North Korean nuclear strike from their list of pressing concerns.

Mr. Moon clearly understands that Mr. Kim’s economic ambitions are the key to keeping the diplomatic process going. On his visit to Pyongyang this week, Mr. Moon brought the heads of state-backed rail and energy corporations, along with the CEOs of South Korea’s top conglomerates. No deals were struck, and the group has been mum so far about its meetings. But its presence was enough to send the message that South Korea stands ready to move forward with major economic cooperation projects with the North.

In one astonishing scene, Mr. Moon addressed a crowd of 150,000 cheering North Koreans and pledged to “hasten a future of common prosperity.” He praised Pyongyang’s “remarkable progress” and said he understood “what kind of country Chairman Kim and his compatriots in the North want to build.” In a formal agreement known as the Pyongyang Declaration, the two leaders committed to reconnect rail and road links between the two countries, reopen a frozen joint industrial zone in Kaesong and a tourist site at Mount Kumgang, and make plans for a special economic zone, of the kind Deng promoted to open up China to foreign investment in the 1980s.