U-S President Donald Trump has announced his defence secretary, Jim Mattis, will retire at the end of February.
The announcement comes a day after Trump surprised U.S. allies and members of Congress by announcing the withdrawal of American troops from Syria.
Mattis, a former Marine general, had clashed to Trump over the withdrawal, as well as the president's go-it-alone stance in world affairs.
He told Trump in a letter he's leaving because — as he puts it — ''you have a right to have a Secretary of Defence whose views are better aligned with yours.''