Transcript for Trump, Kim Jong Un sign joint document at historic meeting

on this Tuesday morning and an storic morning. The first meeting bween an American president a a leader of North Korea. You see Georg there in Singapore leading our coverage moments ago and, George, there weremany extraordinary moments. Surreal is the word for, robin. That is exactly the wordhat Kim Jong-un himself used calling it L a scieniction movie. That was right after this moment that kicked it all off, that historic handshake between president trump and Kim Jong-un. Hard to believe that just a few months ago they were calling each other name, threaning each other with nuclear annihilation. Really is hard to believe, George. The two, they're sitting down and sat down together. They signed that agreement overnight an beforehat president trumshowing Kim Jong-un his limousine called the beast. The two spending nearly five hours together. Just moments ago president trump taking off from Singapore heading back to the United States and as we said before he left, George, you sat down with him for tt exclusive interview. Amy, right inhe room WHE it all happened, right before th table where they si, the agreement, the president bounded into the room saying he had been up for 24 hours straight and here with Jon Karl, Jon, what a 24 hours it has been. George, an iredible series of images, incredible moments, things that would not have seemed imaginable until you actually saw them take place and thesident seemed to relish every minute of it. Clearly sees this as the defining moment of his presidency. President trump and Kim Jong-un emerged from their summit lookin like old friends. What surprised you the most about chairmankim? Great personality. Very smart. Combination. Reporter: The president who once slammed Kim as little rocket man hailed today as a great talent and a worthy negotiator. Will beou meeting again, sir? We'll be meeting many tis. Reporter: A remarkable turn from the nuclear brinksmanship from weeks ago trump and Kim king what might prove to be a momentous step towards peace. Both leaders signed a jnt document committing took Korean peninsula. President trump holding up those signatures for the world to see. Kim Jong-un said they decide to leave the past beh and that the world will see major change. Mr. President, did he agree to denuclearize, sir. We're starting that process very, very qly. Ablutely. Orter: But the agreement is short on specifics. Like whether the denuclearization will be verifiable and irreversible and it comes with significant concessions from the president. Guarteeing Kim's secy even vowing to end joint military exercises with South Korea. And the agreement including no mention of human rights. Whatever the ultimate outcome, story was me with that first handshake. It's my great honor. Reporter: At F stern faces before the Caras, those turned to smilend even lahter. Kim even noting the surrealness of the moment. Many people in the world will think of Thi as from a science fiction movie, H said. It will be tremendously kesful and it's my honor and we wi have a terrific relationship, I have no doubt. Eporter: It was not an easy pathhere, Kim said, but we've overcome evething and come to this place. For the north Koreans it meant putting aside their disgust with U. National suritydviser John Bolton, a man they once called human scum. Lton was seat add cross the north Korean delegation during the lunch. The president attempting to lighten the mood with a joke. Getting a goo picture, everyone? So we look nice and handsome and thin? Perfect? Reporter: The presideven gave Kim a look inside his armored Cadillac known as the beast. Thrust into the spotlight Kim smiled a played along. But S cautious andeserved. Mr. Presint, will you invite chairman Kim to the white house? Absolutely, I will. Mr. Kim, would you like T come to Washington? Thank you. Thank you, everybody. Reporter: There are so many details to be wd out. Particularly, George, on the issue of denuclearization. The president couldn't even say today how long this process would take but H did say he directed Mike Pompeo and his national security adviser John Bolton to begin the process of talking -- following up one north Koreans next ek. This is just the begiing.

This transcript has been automatically generated and may not be 100% accurate.