Transcript for Trump tries to rally supporters on North Korea meeting
of the month. Now to the latest on north Korea. President trump driving ahead with the planned summit after a snap decision to sit face to face with Kim Jong-un. The president talked about that at a raucous campaign rally in Pennsylvania. Reporter: President trump seems as positive about this meeting as he could be. Even scolding the crowd for booing the north Korean leader who he has consistently belittled. President trump sounding optimistic over the weekend at a campaign rally in Pittsburgh, after that stunning announcement that the president has agreed to a face-to-face meeting with north Korean leader Kim Jong-un. They're not going send missiles up. Think of it. They're not sending missiles up. I believe that. I believe that. I do. I think they want to do something. I think they want to make peace. I think it's time. And I think we have shown great strength. Reporter: Trying to sell his supporters on the meeting with the dictator he once called little rocketman. Kim Jong-un. And -- no, it's very positive. No, no. After the meeting, you may do that. But flow we have to be very nice. Let see what happens. Reporter: Sources tell ABC news that the demilitarized zone is the most likely location for the meeting, which South Korea has said could happen as early as Y. Over the weekend, Jim Mattis leaving questions about north Korea to the diplomats, emphasizing how precarious this effort remains. I don't want to talk about Korea at all. I'll leave it to those leading the the effort. It's that delicate. When you get into a position like this. The potential for misunderstanding remains very high or goes higher. Reporter: As for the north key yans, as of this morning, they have not uttered a word publicly about the planned meeting since president trump abruptly accepted the north's invitation last week. Officials in South Korea say they have been kept in the dark, as well, George. A lot more to learn. Let's bring in Jon Karl for
This transcript has been automatically generated and may not be 100% accurate.