Factbox: Outgoing Pentagon chief Mattis was often at odds with Trump

U.S. Defense Secretary Jim Mattis will quit in February after falling out with Donald Trump over the president's foreign policies, including the surprise decision this week to pull troops out of Syria and plan a drawdown in Afghanistan.Mattis, a retired Marine general who embraced NATO and America's traditional alliances, laid bare his division with the president in a resignation letter that underscored what have been a litany of differences with Trump, albeit without public attacks.The followin