He said the attack took place just steps from the White House and targeted members of the West Virginia National Guard.
"This heinous assault was an act of evil and act of hatred and an act of terror. It was a crime against our entire nation. It was a crime against humanity," Trump said in an address to the nation.
He said the perpetrator will get a harsh punishment for what he did.
"As President of the United States, I am determined to ensure that the animal who perpetrated this atrocity pays the steepest possible price. I can report tonight that based on the best available information, the Department of Homeland Security is confident that the suspect in custody is a foreigner who entered our country from Afghanistan... He was flown in by the Biden administration in September 2021 on those infamous flights that everybody was talking about," Trump said.