President Donald Trump's visit to North Korea has started more calls of outrage against the president, who some feel has forgotten about Otto Warmbier.

On Sunday, Trump became the first U.S. president to set foot in North Korea during a meeting in the Demilitarized Zone with Kim Jong Un.

"It's just an honor to be with you and it was an honor that you asked me to step over that line," Trump told the North Korean leader. "And I was proud to step over that line."

Trump added that it was "a great day for the world."

But many were outraged by the meeting due to North Korea's treatment of Otto Warmbier, a 21-year-old college student from the Cincinnati suburb of Wyoming, who died shortly after being returned to his family after 15 months in captivity in North Korea.

"Trump just cited return of US hostages as a sign of goodwill from North Korea, seeming to forget Otto Warmbier was returned brain damaged and near death," said CNN host Jim Sciutto.

"Trump just did a disgustingly chummy photo op with the dictator of a murderous regime that killed Otto Warmbier," Ohio Dems said on Twitter.

Many users included the hashtag #TrumpRewardsOttosMurderer in tweets.

Otto Warmbier was ending a visit to North Korea in January 2016 when authorities arrested him at the airport. Three weeks later, he delivered a stilted “confession” to stealing a poster from a hotel.

In March 2016, Warmbier was convicted in a show trial of crimes against the state and sentenced to 15 years at hard labor. For 15 months, the family heard nothing about the University of Virginia student from suburban Cincinnati.

In June 2017, the North Korean government released Otto Warmbier, but he returned to Cincinnati with a massive brain injury that had left him blind, deaf and unable to move under his own power. Otto Warmbier died June 19, 2017, at 22.

Otto's parents have been outspoken critics of North Korea since their son's death. The family won a lawsuit filed against the country, awarding them $500 million.

Citing the isolated nation's "barbaric mistreatment of Otto," the federal judge said parents Fred and Cindy Warmbier of Wyoming, Ohio, provided evidence North Korea had taken him hostage and tortured their son. She said the country "deliberately caused Otto's brain damage, which resulted in his death."

“North Korea to me is a cancer on the earth. And if we ignore this cancer, it’s not going to go away. It’s going to kill all of us,” Cindy Warmbier said. “Otto was all about love and goodness. He always saw the best in people. ... So I know when they took Otto, he thought he’d be released."

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It's not the first time Trump has faced backlash due to his relationship with the North Korean Leader.

In February, Ohio Sen. Rob Portman, pleaded with American to "Remember Otto" as President Trump meets this week with North Korea leader Kim Jong Un.

"Let's not forget about what they did to Otto and other human rights violations being committed in North Korea," Portman, a Terrace Park Republican, said Tuesday during a conference call with Ohio journalists. "This is not a country to be let off the hook."

Politicians and diplomats across the spectrum expressed disbelief in March at President Trump’s assertion that North Korean leader Kim Jong Un did not know what happened to Otto Warmbier while the Wyoming, Ohio man was in Pyongyang’s custody.

Here's what Twitter had to say:

USA TODAY contributed to this article.