Transcript for North Korea threatens to cancel summit with U.S.

Now to that new threat from North Korea saying they could cancel the summit with president trump as the U.S. And south Korea conducted chief military drills. Martha Raddatz has the latest and, Martha, North Korea saying they will not be pressured into giving up their nuclear weapons. Good morning. Reporter: Good morning. The negative rhetoric coming from North Korea escalated overnight into this morning threatening the summit that has seemed a certainty. Overnight, a sudden roadblock ahead of the highly anticipated summit between president trump and Kim Jong-un. North Korea's vice minister for foreign affairs and former nuclear negotiator threatening to pull out of the meeting if the U.S. Insists on unilateral nuclear abandonment and taking direct aim at president trump's new national security adviser John Bolton, saying we do not hide our feelings of repug nance towards him. Bolton talking about denuclearization on Sunday's "This week." Implementation of the decision means getting rid of all the nuclear weapons. Reporter: The tough words come hours after North Korea canceled today's talks with South Korea over ongoing u.s./south Korea military exercises. The north Korean central news agency adding this, the united States will also have to undertake careful deliberations about the fate of the planned north korea/u.s. Summit in write of this provocative military ruckus. The about-face seemed to catch the state department by surprise. We have not heard anything from that government or the government of South Korea to indicate that we would not continue conducting these exercises. Reporter: And at that triumphant late night return of those American prisoners, president trump made it clear he has high hopes for his meeting with Kim Jong-un. I really think he wants to do something and bring that country into the real world. Reporter: But today the reality of dealing with the mercurial north Korean leader is setting in. The U.S. And South Korea had postponed military exercises during the olympics but will not cancel the current exercises that are happening right now. Could this be a negotiating tactic by them? It sure could be. They could be saying, let the games begin right now and figure out what they want from the United States. You know, we've been asking this question over and over again, what do they want? They freed the prisoners and said originally they'd denuclearize. Now it looks like they're in a negotiating stage. The one thing we know Kim Jong-un is as unpredictable as president trump. That is a certainty. Thank you, Martha.

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