WASHINGTON - US Defense Secretary Jim Mattis, a retired Marine Corps general who was known as a stabilizing force in President Donald Trump's Cabinet, will leave his job at the end of February, Trump said in a tweet on Thursday.
His departure had been anticipated since Trump announced on Wednesday that he was withdrawing US troops from Syria despite opposition from US allies and top US military officials.
Mattis said in his resignation letter that he was stepping down so Trump could have a defense chief whose views align more closely with his own.
Trump said he would nominate a successor to Mattis shortly.
Mattis joins a long list of former Trump administration senior figures who have either quit or been removed, some unceremoniously like Secretary of State Rex Tillerson who Trump fired via Twitter in March.
Trump's White House has had the highest turnover of senior-level staff of the past 5 presidents, according to the Brookings Institution think tank.
Speculation that Mattis might not last long in his post grew in October when Trump said in a CBS interview that the general was "sort of a Democrat" and might be leaving.