President Trump, speaking from Camp David Saturday in the middle of his retreat with key congressional leaders and senior administration officials, said he would "absolutely" engage in phone conversations with North Korean leader Kim Jong Un.

The president made the decision to address reporters about his administration's 2018 legislative agenda Saturday, but when reporters began asking questions, Mr. Trump veered off message to address North Korea, questions about his mental fitness and the Russia investigation. Hours earlier, faced with criticisms in Michael Wolff's bombshell book "Fire and Fury: Inside Trump's White House," the president took to Twitter from Camp David to defend himself, saying he is "like, really smart" and "a very stable genius."

Senior officials in his administration have suggested there must be some preconditions to talks with North Korea. In mid-December, Secretary of State Rex Tillerson said he would be open to speaking with North Korea without preconditions, before backtracking on that statement and insisting North Korea must first reduce the threat of its nuclear weapons program. McMaster in December insisted Tillerson's initial comment was incorrectly reported.

Get Breaking News Delivered to Your Inbox

On Saturday, asked if he would be willing to engage in a phone conversation with the North Korean leader right now, Mr. Trump said, "I always believe in talking."

"Our stance, you know what it is. We're very firm," Mr. Trump continued. "But I would be -- absolutely, I would do that. No problem with that, at all."

But the president, asked if that meant no prerequisites to coming to the table, said, "That's not what I said, at all."

"Look, right now they're talking Olympics," Mr. Trump said of North Korea and South Korea. "It's a start. It's a big start. If I weren't involved they wouldn't be talking about Olympics right now. They'd be doing no talking or it would be much more serious. He knows I'm not messing around. I'm not messing around. Not even a little bit. Not even 1 percent. He understands that."

The president also answered a question about why he would tweet to defend his mental abilities. He said he went to the "best" college and was an "excellent" student who went on to succeed in business, on TV, and at the ballot box.

"And then I hear this guy that doesn't know me, doesn't know me at all," Mr. Trump said, adding that a conversation Wolff claims occurred, "didn't exist, OK, it's in his imagination."

"I consider it a work of fiction," Mr. Trump said of Wolff's book.

The president also suggested that the "libel laws are very weak in this country. If they were strong it would be very helpful."

Mr. Trump also addressed a New York Times story from earlier this week that claims he told the top White House lawyer to make sure Attorney General Jeff Sessions didn't recuse himself from the Justice Department's Russia investigation.

"The story by the way in the Times was way off, or at least, off," Mr. Trump said.

Asked how the story was off, Mr. Trump said, "You'll find out. But the story was off."

The president said he still has faith his attorney general.

Looking ahead to the 2018 agenda, the reason for the Camp David retreat, Mr. Trump said a fix for the Deferred Action for Childhood Arrivals (DACA) program cannot happen without stronger security. Protections for DACA recipients end March 5, without further action.

"We all want DACA to happen, but we also want great security for our country," Mr. Trump said.

In other news at Camp David, White House chief of staff John Kelly told pool the retreat was going "really good -- very good" and that the commander in chief hunkered down Friday night and watched "The Greatest Showman" starring Hugh Jackman and Zac Efron. Kelly said that congressional leaders and Cabinet secretaries were also in attendance.

Kelly said he thought he would have to "suffer through it," but actually enjoyed the film and spent the night relaxing and having a "couple glasses of wine."