WASHINGTON, Dec 7 - U.S. President Donald Trump on Friday blasted his former secretary of state, Rex Tillerson, in a sharply critical tweet one day after the nation's former top diplomat publicly recounted that the president had tried to do things in a way that violated 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 wrote.