Donald Trump invites Kim Jong Un to meet him at DMZ; North Korea calls offer 'very interesting'

President Donald Trump elaborated on his invite to North Korean leader Kim Jong Un to meet him at the demilitarized zone, telling reporters he "just thought of it this morning."

"All I did is put out a feeler if he’d like to meet," Trump said in response to a question from ABC News' Karen Travers during a pool spray of a breakfast with Mohammed bin Salman of Saudi Arabia. "He sent me a very beautiful card and I guess he got my return letter."

"But I just thought of it this morning," Trump said, emphasizing the spontaneity of his invitation.

North Korea responded to the offer, calling it "very interesting," according to The Associated Press.

Trump had said it would be a brief encounter, if it happens at all.

"I let him know, and we'll see if he's there, we'll see each other for two minutes that's all we can but that will be fine," Trump said.

In talking about visiting the demilitarized zone (DMZ) that separates North and South Korea, the president vacillated between saying that he is in fact going -- with some certainty -- but then also saying less definitively that he "may go."

"We’ll be at the area, we may go to the DMZ, the border as they call it, that by the way when you talk about a wall when you talk about a border that’s what they call a border," Trump said. "Nobody goes through that border, just about nobody. That’s called a real border, but we’re going there we’re going to look at it. It’s really a point of interest."

"So we’ll be there and I just put out a feeler because I don’t know where he is right now, he may not be in North Korea, but I said if Chairman Kim would want to meet, I’ll be at the border," Trump said. "We seem to get along very well, that’s a good thing not a bad thing."

The president also asserted that the U.S. would be at war with North Korea if not for his diplomatic efforts.

"Frankly, if I didn’t become president, you’d be at war with North Korea, you’d be having a war right now with North Korea, and by the way that's a certainty," he contended. "That’s not like, 'maybe.'"

Seated across from the Crown Prince, Trump referred to the prince as a "friend of mine" and praised him for "opening up" Saudi Arabia.

The president ignored questions about the murder of Washington Post journalist Jamal Khashoggi.

The president’s meeting with the crown prince came a week after a new United Nations (UN) report released last week said that further investigation should be done into the role of Saudi leadership, including the crown prince, in Khashoggi’s death.

Prior to his trip to Japan, the president spoke to the crown prince by phone and later said he didn’t raise the issue of the report with him in that call. The president has also suggested he’s not inclined to take the report’s advice for the FBI to investigate Khashoggi’s death further, saying Khashoggi’s death has already been investigated.

ABC News' Amanda Maile contributed to this report.