Mattis said on Thursday he would quit after falling out with Trump over the latter’s foreign policies, including the surprise decision to pull troops out of Syria and plans for a drawdown in Afghanistan. “Secretary Mattis has made a key contribution to keeping NATO strong and ready to deal with the significant security challenges we face,” NATO spokeswoman Oana Lungescu said. “He is widely respected as a soldier and a diplomat.” Mattis has been seen in Europe as firmly committed to the North Atlantic Treaty Organization (NATO) military alliance, unlike his ex-boss.