SINGAPORE — In galvanizing international condemnation of North Korea last year, President Trump often invoked the authoritarian nation’s brutal mistreatment of foreign prisoners and its own people, some of whom, he said in Seoul in November, “would rather be slaves than live in North Korea.”

But on Tuesday, after a five-hour summit with leader Kim Jong Un, Trump showed up for a triumphant news conference in front of hundreds of international journalists and didn’t mention human rights in his opening remarks.

The issue wasn’t included in a joint statement signed by the two leaders. And although Trump, in response to a question, assured reporters that he raised the matter with Kim, the president did not offer anything specific about what they discussed.

Even his characterization of North Korea as a brutal dictatorship had grown more equivocal after meeting its 34-year-old leader. During his speech in Seoul, Trump had called conditions in the rogue nation “a hell that no person deserves.” At his State of the Union address in January, Trump surprised his audience by hailing the bravery of a North Korean defector seated in first lady Melania Trump’s box, an emotional moment that drew a standing ovation in the House chamber.

By contrast, Trump on Tuesday took pains to remind his audience that while life is “rough” in North Korea, “it’s rough in a lot of places, by the way, not just there.”

The president’s muted tone on human rights came as he suggested that, by engaging in a dialogue, Kim had put his country on a path toward peace and prosperity, as well as a measure of political normalization in its relationship with the United States.

The outcome of Trump’s summit drew backlash Tuesday from his political opponents.

“Kim’s gulags, public executions, planned starvation, are legitimized on the world stage,” Sen. Chris Murphy (D-Conn.) wrote on Twitter, adding that Trump gave up too much to Kim by agreeing to end joint military exercises between U.S. and South Korean forces.

“What the hell?” Murphy asked.

Trump said more working-level meetings among aides would begin soon as the two sides hammer out details on how to move forward over denuclearization talks. But he made no mention of trying to win commitments from Kim to release political prisoners or close the hard-labor camps to which an estimated 100,000 North Koreans have been sentenced.

Forty-five minutes into the news conference, a reporter challenged Trump: “I wonder what you would say to the group of people who have no ability to hear or see this press conference, the 100,000 North Koreans kept in a network of gulags. Have you betrayed them by legitimizing Pyongyang?”

The president bristled.

“No, I think I’ve helped them,” he replied. “There’s nothing I can say. All I can do is do what I can do. We have to stop the nuclearization.”

Ultimately, Trump said, imprisoned North Koreans are “going to be one of the great winners, as a group.” But he did not explain why he felt so confident.

Trump’s shift in tone is particularly remarkable given that it was after the death, one year ago Wednesday, of Otto Warmbier, an American college student who had been held captive in North Korea for 17 months for taking a propaganda poster, that the president had appeared to take a harder line on Pyongyang last year.

Aides said Trump, who has prided himself on helping win the release of 17 Americans from foreign jails, was personally moved by Warmbier’s story. The president has offered personal support to Warmbier’s parents, Fred and Cindy, including calling them several weeks ago. The family has filed a federal lawsuit against North Korea, accusing it of having “brutally tortured and murdered” Otto, a move made legally possible when Trump ordered North Korea returned to the list of state sponsors of terrorism.

“I think without Otto, this would not have happened,” Trump said of the nuclear summit. “Something happened from that day, a terrible thing,” he said. “It was brutal. A lot of people began focusing on what was going on. Including North Korea. I really think that Otto is someone who did not die in vain.”

Trump cited Warmbier’s case as he made a successful push to win the release of three American prisoners from the North last month in a goodwill gesture from Kim.

In a statement issued later Tuesday, Warmbier’s parents, Fred and Cindy Warmbier, said, “We appreciate President Trump’s recent comments about our family. We are proud of Otto and miss him. Hopefully something positive can come from this.”

Since taking power in 2011 after the death of his father, Kim has proved himself to be as ruthless as his forebears. He is thought to have been involved in the plot to assassinate his own half brother, Kim Yong Nam, at a Malaysian airport in 2017 — a killing that eliminated a threat to his legitimacy as the nation’s ruler.

Kim is believed to have ordered the killings of other family members and political rivals in a successful bid to consolidate power.

Over the decades, the North Korean regime also has abducted South Korean and Japanese citizens, and the issue is among the most salient and emotional in Tokyo.

Ahead of Trump’s summit with Kim, Japanese Prime Minister Shinzo Abe pleaded with the president to raise the issue of 12 Japanese nationals who were abducted in the 1970s and 1980s.

“I brought it up, absolutely,” Trump said, when asked about the Japanese abductees. “And they’re going to be working on that.” But he suggested that it was a matter to be resolved by Kim and Abe directly, even though there is no plan for a summit between them.

Near the conclusion of the news conference, another reporter pressed Trump on whether he had missed a chance to hold out on a summit until Kim took steps to curb human rights abuses.

“I think we answered that,” Trump said.