Instead, during a two-day visit to South Korea's capital, within range of North Korean artillery, Trump spoke in unusually measured tones for him, and offered North Korea's ruler "a path to a much better future" if he would give up his nuclear weapons entirely.
In a sober speech to the South Korean National Assembly on Tuesday, Trump described a vivid contrast between what he called "the miracle" of prosperous and free South Korea and "the prison state of North Korea," with its poverty, forced labor, torture and oppression — "a hell that no person deserves."
As condemnatory as Trump was toward the North, his message was mostly a diplomatic appeal of the sort he only recently told his secretary of State, Rex Tillerson, was a waste of time. At one point Trump spoke as if directly to North Korea's Kim, saying, "The weapons you are acquiring are not making you safer, they are putting your regime in great danger.
"We are ready to offer a path to a much better future," he said.
The president delivered threats as well. "Do not underestimate us. Do not try us," he said, adding, "The world cannot tolerate the menace of a rogue regime that threatens with nuclear devastation."
He noted the firepower the U.S. currently has on the Korean peninsula, including three carrier strike groups "loaded to the maximum" with F-35 and F-18 fighter jets and a nearby nuclear submarine. "We will not allow American cities to be threatened with destruction," he said.
Trump also demanded that every nation "sever all ties" with North Korea. For any country that "enables" Pyongyang, he said, "the weight of this crisis is on your conscience" — a comment that seemed directed at China, North Korea's biggest trading partner and the next stop on Trump's Asia tour.
His address drew praise from a longtime Asia scholar, Orville Schell, who was in the audience. “It was hard hitting, it was coherent and he stuck to the teleprompter,” Schell said. By putting countries like China "on notice that they, too, are responsible for North Korea,” Trump “adeptly” teed up his meetings with Chinese President
Before his address, in what was intended as a defiant gesture toward Kim, Trump tried to make a dramatic surprise visit to the highly fortified border between North and South Korea on Tuesday. His helicopter had to turn back because of severe fog just miles from the demilitarized zone.
Trump had made his first overtures to North Korea the day before, during a joint news conference with South Korean President Moon Jae-in. "It makes sense for North Korea to come to the table and make a deal," he said.
"I do see certain movement, yes," Trump said. "But let's see what happens."
He offered no specifics, noting that his administration likes "to play our cards a little bit close to the vest."
White House advisors had been counseling Trump for months to not attack Kim personally and instead to make the case that it was in North Korea's interest to give up its nuclear program, bring an end to international sanctions and rejoin the global community.
The shift from incendiary rhetoric to talk of negotiations came after Trump spent a long afternoon of talks, a walk through the woods and an elaborate state dinner with Moon the day before. The South Korean leader, who was elected promising to make overtures to North Korea, but who has hardened after Kim's repeated provocative missile tests, agreed to push forward with plans to purchase more U.S. reconnaissance equipment and larger missile batteries.
Trump went further, touting South Korea's promise to buy "billions" of dollars' worth of U.S.-made military equipment. As he did in Japan, Trump said such purchases would have dual value: making the nations safer while narrowing America's trade deficit with Seoul and creating American jobs.
Moon spoke of the "special bond" he has developed with Trump and said he hoped Trump's visit to the Korean peninsula "will be a turning point" in the decades-old standoff with North Korea.
Like Trump, Moon called for "maximum pressure" on Kim to convince him to abandon his nuclear weapons program. He also said the U.S. and South Korea are "willing to offer North Korea a bright future" in return.
Moon seems to have developed a friendly though formal rapport with Trump; the two are not so at ease as Trump and Japan's Prime Minister Shinzo Abe, who called each other "Donald" and "Shinzo" during Trump's earlier stop in Japan as he opened his five-nation Asia tour.
Shortly after Air Force One landed in South Korea on Monday afternoon, Trump and Moon ate lunch with South Korean and American troops at Camp Humphreys, the hub for nearly 30,000 U.S. military troops on the peninsula.
On streets near the South Korean presidential mansion, called the Blue House for the color of its traditional tiled roof, protesters held signs reading "No Trump" and "No war."
Other onlookers waved U.S. and South Korean flags. Hundreds of Seoul police officers stood at major intersections in rows several officers deep to stop marchers from getting too close to the compound.
Inside the Blue House, Moon was effusive in his compliments, congratulating Trump on the upcoming anniversary of his election victory, the strong U.S. economy and record-high stock market.
"You are already making great progress on making America great again," he said.
He also praised Trump for putting North Korea "at the top" of his list of security concerns.
In September, Trump publicly criticized Moon's policy, saying his "talk of appeasement" with the North was doomed to fail.
Opinion polls show South Korean voters overwhelmingly approve of Moon's performance in office so far, but are wary of Trump and worried he will start a war.
In spring 2015, about 88% of South Koreans in a Pew Research Center survey said they trusted the American president to "do the right thing regarding world affairs." Two years later, that share has fallen to 17%, according to the center's global attitudes poll.
Moon was elected in a landslide in May after campaigning on promises to reach out to North Korea. He has shown a willingness to take a harder line in recent months following a series of ballistic missile tests by Pyongyang, including two that indicated it has developed intercontinental ballistic missiles capable of reaching the U.S. mainland. This month, Moon's government artfully convinced China to stop calling for boycotts of South Korean products in retaliation for the placement of high-tech U.S.-made ballistic missile batteries to repel a potential North Korean attack. China objected to having such sophisticated American military equipment so close to its border.
On the next stop in Beijing, Trump will try to convince China's leader Xi to further squeeze the North Korean economy and cut off exports into North Korea, the vast majority of which come from China.
Special correspondent Matt Stiles in Seoul contributed to this report.
9:15 p.m.: This article was updated with reporting on Trump's address to South Korea's National Assembly.