Trump rages at 'lazy' Rex Tillerson: He lacked the 'mental capacity' to be secretary of state
Donald Trump addresses the Kansas State Republican caucus. (mark reinstein /

Donald Trump on Friday attacked Rex Tillerson, after his former secretary of state said the president was undisciplined and wanted to violate the law.

"Mike Pompeo is doing a great job, I am very proud of him. His predecessor, Rex Tillerson, didn’t have the mental capacity needed. He was dumb as a rock and I couldn’t get rid of him fast enough. He was lazy as hell. Now it is a whole new ballgame, great spirit at State!" Trump tweeted.

Tillerson, who was fired in March via a tweet, said Thursday night that Trump had to be repeatedly warned that his proposals were illegal.

“So often, the president would say, ‘Here’s what I want to do and here’s how I want to do it,'” he explained. “And I would have to say to him, ‘Mr. President I understand what you want to do but you can’t do it that way. It violates the law.'”

"It was challenging for me coming from the disciplined, highly process-oriented ExxonMobil Corp to go to work for a man who is pretty undisciplined, doesn't like to read, doesn't read briefing reports, doesn't like to get into the details of a lot of things," Tillerson added.

During his time as Trump's secretary of state, Tillerson was accused of describing the president as a "moron" in a Pentagon meeting.