Washington (CNN) President Donald Trump's decision not to hold North Korean dictator Kim Jong Un responsible for Otto Warmbier's death was "reprehensible," former Republican Sen. Rick Santorum said Thursday.

"This is the conundrum of Donald Trump for many of us who like his policies and don't like a lot of the things he does and says," Santorum said of the decision to CNN's John Berman on "New Day."

"But, this is reprehensible, what he just did. He gave cover, as you said, to a leader who knew very well what was going on with Otto Warmbier," Santorum, who is a CNN political commentator, said. "And again, I don't understand why the President does this. I am disappointed, to say the least, that he did it."

Earlier Thursday, Trump, who was in Hanoi for a summit with Kim , said the North Korean leader "felt badly about it. He felt very badly," telling reporters the two discussed the matter privately. "He tells me that he didn't know about it and I will take him at his word."

North Korea released Warmbier, an American student, in June 2017 after more than a year of imprisonment, returning him to the US in a coma. Warmbier died days after returning home and US officials quickly blamed North Korea for the brain damage Warmbier suffered that led to his death.

Read More