WASHINGTON (AP) — Defense Secretary Jim Mattis resigned Thursday after clashing with President Donald Trump over the abrupt withdrawal of U.S. troops from Syria and after two years of deep disagreements over America's role in the world.

Mattis, perhaps the most respected foreign policy official in Trump's administration, will leave by the end of February after two tumultuous years struggling to soften and moderate the president's hardline and sometimes sharply changing policies. He told Trump in a letter that he was leaving because "you have a right to have a Secretary of Defense whose views a...