Jim Mattis resigns

Defense Secretary Jim Mattis, whose experience and stability were widely seen as a balance to an unpredictable president, resigned Thursday in protest of President Trump’s decision to withdraw American forces from Syria and his rejection of international alliances.

Mr. Mattis had repeatedly told friends and aides over recent months that he viewed his responsibility to protect the United States’ 1.3 million active-duty troops as worth the concessions necessary as defense secretary to a mercurial president. But on Thursday, in an extraordinary rebuke of the president, he decided that Mr. Trump’s decision to withdraw roughly 2,000 American troops from Syria was a step too far.

Officials said Mr. Mattis went to the White House with his resignation letter already written, but nonetheless made a last attempt at persuading the president to reverse his decision about Syria, which Mr. Trump announced on Wednesday over the objections of his senior advisers.