By now, I was accustomed to his chipper declarations about an imminent cataclysm, but this one baffled me. He explained, “Everything here has a dual-use purpose.” He pointed to an underpass, beneath an intersection, which he said can serve as a shelter. In the back yards of apartment blocks, residents can take cover in storage cellars. Surrounded by commuters, we boarded an escalator, heading down to the station.

Built in the seventies, with Russian help, the Pyongyang Metro lies a hundred metres underground, nearly twice as far as the deepest platform in the New York City subway. Pyongyang stations are equipped with large blast doors. “During the Korean War, we were threatened by nukes,” Pak said. In 1950, President Truman raised the possibility of using the atomic bomb in Korea. “It touched our people’s minds,” he said, adding, “We don’t want that to happen again. And now we’ve got nukes and we can comfortably say, ‘Let’s do it.’ ”

In the event of a nuclear war, American strategists assume that North Korea would first launch a nuclear or chemical weapon at an American military base in Japan or Guam, in the belief that the U.S. would then hold its fire, rather than risk a strike on its mainland. I mentioned that to Pak, but he countered with a different view. “The point of nuclear war is to give total destruction to another party,” he said. “There are no moves, no maneuvers. That’s a conventional war.”

When we reached the subway platform, we were treated to patriotic orchestral music playing on the loudspeaker. Broadsheet newspaper pages were hung behind glass for people to read while they waited for the train. The scene reminded me of thirty-year-old photos I’ve seen of Beijing. We rode the train awhile, and then got on the escalator for the long ascent to the surface.

I was glad to be back in the open air. We got in the Toyota, and Pak said, “If the U.S. puts sanctions and sanctions and sanctions and sanctions, if they drive us to the edge of the cliff, we will attack. That’s how the world wars have started.” He thought awhile and then said, “Don’t push us too hard, because you’re going to start a war. And we should say, we’re not going to die alone.”

This was a familiar refrain. Some of the American officials in Washington who are immersed in the problem of North Korea frequently mention the old Korean saying “Nuh jukgo, nah jukja!” It means “You die, I die!” It’s the expression you hear in a barroom fight, or from an exasperated spouse—the notion that one party will go over the cliff if it will take the other down, too. Krys Lee, a Korean-American author and translator, said, “My mother also used it on me!” Lee finds that it’s hard for Americans and Koreans to gauge each other’s precise emotions, because Koreans tend to use “more abstract, dramatic, and sentimental language.” She has heard that many Korean literature students find Raymond Carver—the most laconic of American authors—“very dry, and that he didn’t translate well.”

On my last morning in Pyongyang, I visited the Victorious Fatherland Liberation War Museum. Shortly after Kim came to power, he renovated and expanded it; the museum is now nearly three-quarters the size of the Louvre. Choe Un Jong, a captain in the Korean People’s Army, showed me around. We were the only visitors. (It was a Friday, when, Choe said, the museum is open only to foreigners.) A tall woman in her twenties, Choe had stylish wavy hair that fell to her shoulders. She said, apologetically, “Today I cannot show you all of the museum. It takes three or four days.”

We stood beneath a three-story granite statue of a barrel-chested young Kim Il Sung, looking indistinguishable from his grandson. I told Choe that I had trouble telling their statues apart. She was thrilled. “Without any explanation, people think that that’s Marshal Kim Jong Un!” she said. The exhibits made use of life-size wax figures: there was a Korean commando crouching in the woods, and a dead American soldier with his eyes rolled back and a raven picking at his chest. We walked past captured howitzers and tanks, and a U.S. plane that she said delivered “germ bombs” loaded with “malaria, cholera, and typhoid.” (That claim has been widely debunked.) Choe sat me down for a video called “Who Started the Korean War?,” in which the narrator said, “The Korean War was precisely a direct product of the aggressive foreign policy of the United States to dominate the world.”

The mythology was no surprise, but one exhibit contained a stark implication for the current crisis. Beside the museum, we boarded the U.S.S. Pueblo, a Navy spy ship that was captured in January, 1968, long after the end of the Korean War. The seizure—during a surge of hostilities not unlike the present—was an audacious gamble on North Korea’s part. One American crew member was killed and eighty-two were detained. Lyndon Johnson considered retaliating with a naval blockade or even a nuclear strike. But he was consumed by the war in Vietnam, and, in the end, he did not retaliate. After eleven months, the U.S. apologized for spying and won the release of the prisoners.

The Pueblo incident nearly started a war, but Kim Il Sung drew a powerful, and potentially misleading, lesson from it. In a private conversation in 1971, Kim told Nicolae Ceaușescu, the Romanian President, that the Pueblo and other standoffs had convinced him that Washington backs down. “The Americans don’t want to continue this fight,” he said, according to documents in Romania’s state archives. “They let us know it’s not their intention to fight the Koreans again.”

Van Jackson, a scholar of international relations who served in the Pentagon from 2009 to 2014, spent years analyzing the Kim family’s handling of crises, including the seizure of the Pueblo. The grandfather’s theory of victory still drives North Korea toward provocation, he said, but the regime also knows its limits; to survive, it chooses violence but avoids escalation. “When South Korea blares giant propaganda speakers at the North from the D.M.Z., North Korea fires warning shots nearby but doesn’t dare attack the speakers themselves,” he said. “When South Korean N.G.O.s send propaganda leaflets into North Korea using hot-air balloons—which really pisses them off—North Korea threatens to attack the N.G.O.s but instead just fires at the unmanned balloons.” In Jackson’s view, North Korea is not irrational, but it very much wants America to think that it is.

Jackson believes that the Trump Administration’s threat to launch a preventive war begins a new phase. “Trump may abandon the one thing that has prevented war in the past: U.S. restraint,” he told me. In embracing new rhetoric and rationale, the U.S. risks a spiral of hostility in which neither side intends to start a war but threats and intimidation lead to ever more aggressive behavior. Trump and Kim may goad each other into the very conflict that they are both trying to avoid.

In 1966, Thomas Schelling, the deterrence expert, wrote that brinkmanship hinges, above all, on “beliefs and expectations.” Our grasp of North Korea’s beliefs and expectations is not much better than its grasp of ours. To go between Washington and Pyongyang at this nuclear moment is to be struck, most of all, by how little the two understand each other. In eighteen years of reporting, I’ve never felt as much uncertainty at the end of a project, a feeling that nobody—not the diplomats, the strategists, or the scholars who have devoted their lives to the subject—is able to describe with confidence how the other side thinks. We simply don’t know how Kim Jong Un really regards the use of his country’s nuclear arsenal, or how much North Korea’s seclusion and mythology has distorted its understanding of American resolve. We don’t know whether Kim Jong Un is taking ever-greater risks because he is determined to fulfill his family’s dream of retaking South Korea, or because he is afraid of ending up like Qaddafi.

To some in the Trump Administration, the gaps in our knowledge of North Korea represent an argument against deterrence; they are unwilling to assume that Pyongyang will be constrained by the prospect of mutually assured destruction. But, if the alternative is a war with catastrophic costs, then gaps in our knowledge should make a different case. Iraq taught us the cost of going to war against an adversary that we do not fully understand. Before we take a radical step into Asia, we should be sure that we’re not making that mistake again. ♦

Due to an editorial error, an earlier version of this article misidentified Kim Jong Un’s birth order.

Reporting and photography for this piece was facilitated by a grant from the Pulitzer Center on Crisis Reporting.