Transcript for Biden: Trump's insults 'beneath the dignity' of office of president
President trump is back at the white house tonight after a four-day visit to Japan, where he took aim at his 2020 rival, Joe Biden, while on foreign soil. The president agreeing with what Kim young unhad said about Biden. Tonight, Biden is now responding, and here's ABC's chief white house correspondent Jonathan Karl. Reporter: In Japan, Donald Trump not only ditched the tradition of American presidents avoiding partisan politics when overseas, he said he agreed with an insult north Crete Yan dictator Kim Jong-un directed at former vice president Joe Biden. Kim Jong-un made a statement that Joe Biden is a low I.Q. Individual. He probably is, based on his record. I think I agree with him on that. Reporter: And then, standing next to the Japanese prime minister, he added his own attacks on Biden. In terms of criticism that you're sort of supporting a dictator instead of an American vice president? I can tell you that Joe Biden was a disarser. Reporter: Biden waited until trump was back in Washington before responding. His spokeswoman issuing a statement ten minutes after air force one landed. "The president's comments are beneath the dignity of the to be on foreign soil on memorial day and to side repeatedly with a murderous dictator against a fellow American and former vice president speaks for itself. " The campaign said it's part of a pattern of trump siding with autocrats. In Japan, the president also said he wasn't concerned with North Korea's short-range missile tests earlier this month, directly contradicting his our national security team. You're not bothered at all by the small missiles? No, I'm not. I am personally not. Jon Karl with us live tonight from the white house. And as you reported there, Jon, Joe Biden saying these attacks are below the dignity of the office of the president. Is there any response from the president tonight? Reporter: Well, I asked the president about those comments as soon as he got back here this afternoon to the white house. No response. But just minutes ago, David, he was back on Twitter, again insulting Joe Biden, making no apologies for what he said in Japan, in fact, repeating almost word for word what he said about Biden back there. The 2020 race is here. Jon Karl, thank you.
This transcript has been automatically generated and may not be 100% accurate.