The last time President Trump vowed to halt a country’s nuclear weapons program, he held three face-to-face meetings with Kim Jong-un of North Korea, declared that the two men had developed a “great relationship” and walked away empty-handed.
That was in Mr. Trump’s first term. Not only did the diplomatic effort fail, but Mr. Kim immediately hit the accelerator on his program and today possesses roughly 60 nuclear weapons, by some estimates, as well as missiles that appear capable of reaching the United States — exactly the combination Mr. Trump had vowed to dismantle.
For months now, proliferation experts have questioned whether Mr. Trump could also end up walking away from his efforts to check Iran’s nuclear program — especially now that he appears to be more focused on getting the Strait of Hormuz open than on dealing with Iran’s stockpiles of uranium, which are buried under rubble after the United States bombed them in June 2025.
Stymied in Iran, Mr. Trump is increasingly turning his sights back to North Korea, even though analysts see little hope of quickly dismantling that country’s growing nuclear arsenal.
Mr. Trump’s social media declaration on Sunday night, praising Mr. Kim and publicly ordering Defense Secretary Pete Hegseth to diminish America’s role in an annual military exercise with South Korea, one of America’s allies in the Pacific, appeared intended to signal that he wants to resume negotiations. A day later, it remained unclear just how the Pentagon would scale back its role in the 11-day exercise, and a one-line statement sent to reporters by the Pentagon press office on Monday afternoon did not provide any clarity.
“The Department of War is actively working on executing the commander in chief’s directive,” the statement said, using the Trump administration’s name for the Department of Defense.
Robert Litwak, a scholar at George Washington University who has written about the nuclear programs in both North Korea and Iran, called the contrast between Mr. Trump’s approaches to those two countries “an incredible tale of two rogue states.”
“We’re at war with Iran, a nuclear-threshold state,” he said. “But with North Korea we are placating a dictator who can target the U.S. homeland with nuclear weapons.”
Mr. Trump’s outburst was also aimed at punishing the South Koreans for declining to join in the war against Iran, a position that deeply angered Mr. Trump. It was a point he made in the same social media post and reiterated to reporters in the Oval Office on Monday.
The president has also been angry that Seoul has been slow to deliver on what the White House believes is a $350 billion promise for new investments, including in shipbuilding. Last October, Mr. Trump visited South Korea and celebrated its future investments in the United States, including a promised multibillion-dollar expansion of Samsung’s chip-making plant in Texas.
“Trump defaults back to the complaint about South Korean free-riding” on America’s troop presence on the Korean Peninsula, said Scott A. Snyder, the president and chief executive of the Korea Economic Institute of America, “and he uses the security relationship as a lever to put more pressure on the South Korean government.”
Looming over the tensions is Mr. Trump’s inability to extract the United States from the Iran war. He has hinted at his eagerness in recent months to move on from that conflict and return to dealing with Mr. Kim — who indulged Mr. Trump’s desire for leader-to-leader talks with those summits during Mr. Trump’s first term.
President Lee Jae Myung of South Korea said in June that Mr. Trump appeared to want to resume talks with Mr. Kim, and Mr. Trump posted a picture of himself with the North Korean leader on social media at least twice in recent months.
“Kim Jong Un and I get along GREAT!” Mr. Trump wrote alongside a photograph he posted on Saturday of their meeting at the border between North and South Korea in 2019.
Mr. Trump followed that up with another chummy post on Monday, this one a meme showing Mr. Kim making a phone call with military officers standing behind him. The caption read: “Hey Donald, we cool … right?”
The North Korean nuclear program has been a deep concern since the late 1980s, long before Iran’s nuclear program was on the radar. In 1994, during a crisis triggered by North Korea’s expulsion of international nuclear inspectors, the Clinton administration debated a military strike on the North Korean facility at Yongbyon. But it held back, and later that year former President Jimmy Carter struck a deal with Kim Il-sung, the grandfather of the current North Korean leader, to end the nuclear program in return for help building civilian nuclear reactors.
It all fell apart, and subsequent efforts to bring the North Korean program under control failed. In 2006, the North conducted its first nuclear test, and followed with five more, the most recent in 2017.
The next year, having labeled Mr. Kim “Little Rocket Man,” Mr. Trump met the North Korean leader in Singapore. After their encounter, he told a New York Times reporter that he expected that the North would dismantle its program fast. “It’s going to go very quickly,” he said after the summit. “I really believe that it’s going to go fast. And it is a very substantial arsenal. There’s no question about it.”
But while Mr. Trump recalls the encounters fondly — during the first term, he would bring out Mr. Kim’s letters to him and read excerpts to visitors in the Oval Office — they went down in history as a diplomatic failure. A second summit, in Vietnam, ended with a collapse of the talks. Mr. Trump went into the sessions ill-prepared, his national security adviser at the time, John R. Bolton, said later, and the effort fell apart when Mr. Kim refused to dismantle facilities outside the main enrichment and reprocessing center at Yongbyon.
Some fear the same thing could happen again. “Another Trump-Kim summit, which is what the president seems to be angling for, could be a disaster,” said Joel S. Wit, a former State Department diplomat who was involved in early talks with the North and wrote a history of the effort, “Fallout: The Inside Story of America’s Failure to Disarm North Korea.”
“Trump doesn’t seem to realize that the Kim Jong-un of today isn’t interested in better relations with the United States,” Mr. Wit said. “He is hellbent on keeping his nuclear weapons, sending troops to Ukraine to support his Russian ally and threatening South Korea.”
On Monday, critics of Mr. Trump’s foreign policy quickly attacked the president for undercutting a key alliance. Senator Jack Reed of Rhode Island, the top Democrat on the Armed Services Committee, said Mr. Trump had made “another inane, haphazard decision” that punished South Korea “for no reason beyond Trump’s ego.”
Victor D. Cha, a Georgetown University professor who worked on Asia policy in the George W. Bush White House, described Mr. Trump’s social media outburst as a symptom, at least in part, of the president’s frustration over Iran. He noted that Mr. Trump’s charm offensive directed at Mr. Kim came as the president tried to maintain his hard line against Tehran, a study in contrasts in Mr. Trump’s approach to perhaps the world’s two most vexing nuclear proliferation challenges.
“He’s kind of trending in two opposite directions,” Mr. Cha said. “He’s trending in the direction of pragmatically negotiating with a nuclear North Korea. But in the case of Iran, he’s taken an absolutist stance.”
Mr. Trump defended his approach to North Korea in the Oval Office on Monday. Asked by a reporter whether he was prioritizing the interests of U.S. adversaries over allies, the president shot back: “I’m making it much safer.”
“Kim Jong-un has always treated me with great respect,” the president added. “I understand him. He understands me.”
But Mr. Kim is also closely watching Mr. Trump’s war on Iran, analysts say. That war has shown North Korea, Mr. Cha said, “that they are right to pursue nuclear weapons to avoid a military strike.”
Eric Schmitt contributed reporting.
