Transcript for North Korea cancels planned meeting with South Korea

North Korea, signaling today what could halt that summit between president trump and Kim Jong-un. What the north Koreans want stopped. ABC's chief white house correspondent Jonathan Karl with how the white house is now responding at this hour. Reporter: At the triumphant late-night return of American prisoners, president trump made it clear hem has high hopes for his meeting withim Jong-un. I really think he wants to do something and bring their country into the real world. Reporter: But today, a setback. Angry about annual joint u.s./south Korea military exercises now under way, north Korea abruptly canceled a meeting with South Korea, scheduled for tomorrow. The north Korean central news agency added this message. "The United States will always have to undertake careful deliberations about the fate of the planned north korea/u.s. Summit in light of this provocative military rus Kuck." The developments seemed to catch the state department offguard. North Korea agreed to let the military exercises continue. We have not heard anything from that government or the government of South Korea to indicate we would not continue conducting these exercises. Reporter: It's a setback, but it's hard to tell how big a setback. There had been a remarkable thaw in u.s./north Korea relations. Secretary of state Mike Pompeo greeting Kim Jong-un warmly in bee yom yang. The president was even asked about the Nobel peace prize. I would never say it. Reporter: And the white house raised expectations for the summit even though it is only scheduled to last for a single day. What does the president think can be done in a single day with Kim Jong-un? Certainly, the best outcome would be an agreement for complete and total denuclearization. Let's get to Jon Karl, live at the white house for us again tonight. Bottom line, North Korea indicated those military exercises between the U.S., the south, these joint xer sitzs could tonight, in the runup to this summit. But tonight, a very different message. Is there any indication president trump would put the exercises on hold? Reporter: There is no indication that the U.S. Is willing to stop those exercises. The only word tonight on this comes from the press secretary, Sarah Sanders, who says the United States will continue to coordinate with our allies. We'll be watching this with you, Jon. In the meantime, I wanted to ask you about first lady Melania trump, admitted to Walter reed hospital yesterday. Her office saying she underwent a procedure to treat a, quote, benign kidney condition. It is still unclear exactly what that condition is, but the president visiting her again this afternoon, Jon? Reporter: The president spent a little over an hour with the first lady at the hospital today. We are told that she is doing well and that she is in good spirits. The president himself said this morning, she'll be coming home in two or three days. David? Everyone hoping for a speedy recovery. Jon, thank you. Next, to the Middle East

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