U.S. top diplomat Tillerson says to leave office on March 31

U.S. Secretary of State Rex Tillerson speaks to the media at the U.S. State Department after being fired by President Donald Trump in Washington, U.S. March 13, 2018. REUTERS/Leah Millis

WASHINGTON (Reuters) - U.S. Secretary of State Rex Tillerson, who was fired by President Donald Trump on Tuesday, said he was delegating all of his responsibilities to the State Department's No. 2 official and that he would leave office at the end of the month. "What is most important is to ensure an orderly and smooth transition during a time that the country continues to face significant policy and national security challenges," Tillerson told reporters in a packed briefing room at the State Department. (Reporting by Lesley Wroughton; Writing by Tim Ahmann; Editing by James Dalgleish)