Angered by certain revelations made by his former Secretary of State Rex Tillerson during a critical interview with CBS, US President Donald Trump took to social media to label his one-time chief diplomat as being “Dumb as a rock”, and “Lazy as hell”.

Tillerson was removed by Trump in March this year, after a series of public disagreements over the President’s policies on Russia, Iran, and North Korea.

Since leaving office, Tillerson had continued to offer differing views on a number of US policies, but had largely stayed clear of directly ridiculing Trump until now.

In the interview, Tillerson had told CBS News political contributor Bob Schieffer on Thursday that he had advised Trump that many of his policies were illegal, and would also violate US treaties. In his view, the President did not like him for his stance and firmness on many of the US leader’s decisions.

“I’d have to say to him, well Mr President, I understand what you want to do, but you can’t do it that way. It violates the law, it violates treaty,” said Tillerson.

Obviously disturbed by Tillerson’s utterances, Trump swiftly posted a tweet on feed in which he said that “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!”.