Mattis chooses exactly when he needs to speak, including when to publicly disagree with his commander-in-chief. But he rarely speaks to reporters, and has refused entreaties from Trump staff to make appearances on “Fox & Friends,” one of his boss’ favorite shows. Unlike other Cabinet secretaries and advisers who frequently praise their television-watching boss on the airwaves, Mattis doesn’t do PR.

After watching the Pentagon chief doing diplomatic cleanup with allies after the NATO summit, friends of Mattis’ remarked upon his unique balancing act. William Cohen, former secretary of defense and Republican senator from Maine, told the New York Times: “I think everyone understood that Jim is giving Trump the very best military and strategic advice possible and that he was walking a straight but fine line.”

Supporters of Mattis, across both parties, hope his patriotism will gird him through the choppy waters, and collective fingers across Washington remain crossed that he stays on the job. Yet, as one Republican senator who traveled overseas with him said recently, “It’s getting harder every week.”