U.S. President Donald Trump says he does not believe North Korean leader Kim Jong Un knew about the brutal mistreatment suffered by the late American Otto Warmbier during his imprisonment in the isolated regime.

The 22-year-old University of Virginia student was visiting North Korea with a tour group when he was arrested and sentenced to 15 years of hard labor in March 2016 on suspicion of stealing a propaganda poster. He died the next June after he was returned to the United States in a coma.

During a question and answer session with reporters in Hanoi Thursday, President Trump was asked if he had confronted Kim about Warmbier’s death in 2017. Trump said he really “believed something bad happened to” Warmbier, but said he doesn’t think “the top leadership knew about it.”

“I don’t believe that he would have allowed that to happen,” the U.S. president said, referring to Kim Jong Un. “Just wasn’t to his advantage to have allowed that to happen. Those prisons are rough — they’re rough places, and bad things happen.”

Trump said Kim told him he felt “very badly about it.”

A U.S. federal court judge last November ordered Pyongyang to pay more than $500 million to Otto Warmbier’s family. His parents filed a lawsuit against the reclusive regime, claiming their son had been intentionally beaten. It is unlikely North Korea will pay the judgment since there is no mechanism to force it to do so.