evidence: Blunt and no-nonsense, a retired four-star Marine Corps general deemed so tough on Iran that President Barack Obama’s team often clashed with him, Mattis has turned into the secret "peacenik" of the Trump Administration, as a former government official put it to me last week. A year ago, Mattis had also been wary of the first Trump-authorized missile strike on Syria, at least in the absence of a broader strategy toward the civil-war-torn country that eludes the Administration still. In the year since then, there had been numerous other occasions—some reported, many more not—when a blustering Trump had demanded military action only to run up against the calm but implacable opposition of his defense chief. And that dynamic more or less played out again last week in the White House Situation Room. "He was inclined to a farther-reaching strike," the Republican adviser who spoke with Trump said, "but he deferred to Secretary Mattis."