Rex Tillerson Responds to Damaging Comments Regarding Trump From "Fire and Fury"

Secretary of State Rex Tillerson has never questioned President Donald Trump's "mental fitness" and intends to remain at his post for the entire year, the top US diplomat told CNN in an exclusive interview.

Tillerson was responding to a question about Michael Wolff's explosive book, "Fire and Fury," a detailed look at the first year of the Trump presidency that is raising new questions about the President's temperament.

"I've never questioned his mental fitness," Tillerson told CNN's Elise Labott. "I have no reason to question his mental fitness."

"My relationship with him ... is a developing one," Tillerson said, adding that he hadn't met Trump when he was asked to lead the State Department. "So, we don't have a lot of history in past, so part of this is us knowing -- coming to learn and understand one another," he said.

"In terms of what I would do different, I'm going to build on my ability to communicate with the President better," Tillerson told Labott. "I had to learn is what is effective with this President. He is not a typical of Presidents of the past. I think that's well recognized. That's also the why the American people chose him."

And despite reports that he would soon leave the administration -- either with the help of a hefty push from Trump or under his own steam -- Tillerson said he wasn't going anywhere.

"I have never seen the president leave a meeting with a foreign leader," Tillerson said, adding that "among all the Cabinet secretaries, I probably have spent more time with the President than perhaps Secretary (of) Defense (James) Mattis, who spends a lot of time with him as well."

And in policy deliberations on tough issues ranging from North Korea to Afghanistan to South Asia policy in Pakistan to the ISIS campaign, the President "has been very deliberative, he has listened to the arguments, he argues back as he should ... and in the end, he makes a decision which we then implement," Tillerson said. "I would tell you on all of the major policy areas, the President has made the right decision on every one of those."