North Korea will be at the top of the agenda next week when President Trump welcomes new South Korean President Moon Jae-in for a White House summit.

In his first one-on-one interview since being elected, President Moon spoke to "CBS This Morning" co-host Norah O'Donnell and promised historic change.

"CBS This Morning" co-host Norah O'Donnell and South Korean President Moon Jae-in CBS News

Here are the top takeaways from the interview:

1. Moon Jae-in says Kim Jong Un is "not a rational person," but he wants "dialogue" with Kim.

"President Trump has called Kim Jong Un a madman with nuclear weapons. Do you believe that he is a madman? And why do you wanna talk to a madman?" O'Donnell asked.

"Yes, I have already mentioned that I believe that Kim Jong Un is not a rational person. But I would like to also note that President Trump once even mentioned that he is willing to talk with Kim Jong Un over a burger. And he has another point, he mentioned that it would be an honor to be able to meet Kim Jong Un. So I believe President Trump went much further than I did."

"So I believe what Kim Jong Un would want the most is to have a security guarantee for his regime," Moon added. "So in the case if we can establish a peace regime on the Korean peninsula and if the relationship between the United States and North Korea can be normalized, then I believe that Kim Jong Un would not evade to coming out on such a path. So there is a possibility that Kim Jong Un continues to make the bluff with his nuclear weapons programs. But deep inside he is actually yearning or wanting dialogue. But in the end the only way to find out is to have a dialogue with North Korea."

2. Moon Jae-in believes former President Barack Obama's policy of "strategic patience" was a failure.

"I know you believe that the strategy of President Obama, which was strategic patience with North Korea, was a failure, yes?" O'Donnell asked.

"Yes, I believe in in the end, you cannot deny the fact that strategic patience has failed," Moon said. "And on the same note, I believe that we have no choice but to that we cannot deny the fact that the policies of the Lee Myung-bak administration and the Park Geun-hye administration had failed as well."

3. President Moon praises U.S. President Donald Trump and believes Mr. Trump's greatest diplomatic achievement will be what happens on the Korean Peninsula.

"I had the opportunity to have a telephone conversation with President Trump, and through that call I believe that I have been able to sufficiently build up a relationship of trust and friendship. And during the upcoming summit meeting, I would like to place an emphasis on further strengthening the friendship and trust with President Trump through frank and open discussions," Moon said. "The two of us will be both in office and working together for the next five years. And the two of us also share the common goals of resolving the North Korean nuclear issue, establishing a peace regime on the Korean peninsula, and building peace and security in Northeast Asia. So, if the two of us could pull together and accomplish these common goals, then I believe that this will be the most fruitful achievements that we can achieve during our terms in office. And I also believe that this will be the greatest diplomatic achievements for President Trump as well."

"You believe that his greatest diplomatic achievement will be what happens here on the Korean Peninsula?" O'Donnell asked.

"Yes, that is because President Trump has mentioned that North Korea was on the top of his priority list," Moon said. "And also because this is something that all of the former U.S. administrations could not achieve. And so, I place a – I highly commend President Trump's placing such great importance on the North Korean nuclear issue, and I also believe that thanks to President Trump's approach and attitude, there is a possibility of resolving this issue."

4. Moon Jae-in will not scale back joint military exercises with United States.

"One of your top advisers was just in Washington suggesting that you are considering scaling back South Korea's joint military exercises with United States. Is that true?" O'Donnell asked.

"So I have seen through media reports that my special adviser made such comments," Moon said. "Professor Moon, who is my special adviser, is not a permanent adviser. So my relationship with Professor Moon is rather informal. Professor Moon is an academic. And he continues to freely – be freely active as an academic. And sometimes when I need his assistance, I will ask him for his opinion on certain issues. And what he mentioned in Washington was his personal view."

"And so I believe that there can be many opinions on how we will draw North Korea out to dialogue," he added. "And regarding this I believe the professionals of both Korea and the United States have many differing views on how we will achieve this. But I believe that when it comes to the detailed strategy and tactics on how we will achieve this, this will be – have to be discussed and agreed upon during the summit meeting with President Trump. And I believe that we will need a very strong, close collaboration between Korea and the United States for this – for us to be able to achieve this with any effect."

5. Moon Jae-in hopes dialogue with North Korean leader Kim Jong Un will lead to a freeze of the country's nuclear and missile programs.

"Dialogue in itself is not the end. And I believe that we do not need dialogue for the sake of dialogue. And I have never mentioned a dialogue with no preconditions whatsoever. What I did say was that indicates that North Korea stops its provocations, its nuclear missile provocations, and shows enough will to freeze its nuclear and missile program, then we can begin dialogue -- yes," Moon said. "Since we last had the six-party talks and since the September 19th agreement, a lot has changed. In particular, North Korea has further advanced its nuclear and missile capabilities. Therefore that I believe that it is realistically-- today it is very difficult for to achieve the complete dismantlement of North Korea's nuclear program in one shot. Therefore, I believe that first we must we must vie for a freeze of North Korea's nuclear and missile programs. And then, as a second phase try to achieve the complete dismantlement of North Korea's nuclear program. And I believe there is also some voices supporting such a step-by-step approach even within the United States."

Watch what President Moon had to say about the recent death of American student Otto Warmbier, who was detained by North Korea in January 2016 and released last week in a coma.