Washington ? As Vice President Pence fawningly praised Donald Trump’s achievements at a Cabinet meeting Wednesday, the camera caught Defense Secretary Jim Mattis shuffling his papers, adjusting his water glass and fidgeting in his seat until the adulatory speech ended.

As this year winds down, Mattis remains the good soldier, seated at Trump’s left and guarding his flank, trying to avoid the political fracas of this presidency. He’s the rare Trump appointee who doesn’t seem to have been damaged by his proximity to power. His Pentagon is a force for stability at a time when so many other American institutions are stressed.

Mattis’ only problem may be this bipartisan popularity: He’s the Trump official who’s admired by people who don’t like Trump. That rubs some Trump enthusiasts the wrong way. Former White House adviser Steve Bannon is said to view Mattis as too close to the traditional foreign policy establishment. But Trump himself seems respectful of the retired Marine general he likes to call “Mad Dog.”

The chivalrous Mattis is an unlikely partner for Trump. He’s a Stoic, with an almost superstitious dislike for the spotlight. It’s notable that he has avoided gloating this year about victory over the Islamic State, recalling Gen. Ulysses S. Grant’s refusal to visit Richmond after its collapse to the Union army in 1865. Mattis clearly abhors the political parlor games that are part of Trump’s Washington.

Mattis watched the near-dismemberment this year of Secretary of State Rex Tillerson, his friend and ally. After White House leaks about Tillerson’s prospective firing, Mattis seemed to embrace him more closely in interagency debates. The controversy around Tillerson was a reminder that there’s no “adult swim” in this administration; Trump owns the pool.

Rumors of Tillerson’s death proved premature: He’s still the administration’s point man on North Korea, traveling to Canada this week to discuss new pressures on Pyongyang, including blacklisting ships that have been evading sanctions. Perhaps by keeping Tillerson in place, Trump perversely wants to show that reports of his troubles were just more “fake news.”

Trump insiders still predict that Tillerson will depart sometime in the new year, and that he will be replaced by CIA Director Mike Pompeo. The open, gregarious Pompeo would be an easier fit with Trump, and he appears to have developed a solid working relationship with Mattis as well. Whether Mattis and Pompeo can work well as a team may be crucial for the administration.

Mattis will have continuity at the Pentagon during this period of global turmoil. Joint Chiefs of Staff Chairman Joseph Dunford and Vice Chairman Paul Selva were recently reappointed to additional two-year terms. Patrick Shanahan was confirmed as deputy defense secretary in July; the former Boeing executive is beginning to shape acquisitions and technology decisions, two areas where Mattis is weak.

The rest of Mattis’ team is finally in place. John Rood has been named undersecretary for policy, a key job to which Mattis had once hoped to appoint former Ambassador Anne Patterson. (She was nixed after opposition from Sen. Tom Cotton, R-Ark., among others; Cotton’s rumored appointment to head the CIA if Pompeo leaves might be awkward for Mattis). Adm. Joe Kernan, a former Navy SEAL, is undersecretary for intelligence. Ellen Lord, a former CEO of Textron, is undersecretary for acquisitions.

The trickiest challenge for Mattis next year will be North Korea. The defense secretary backs Tillerson’s strategy of diplomatic pressure; the goal is slow asphyxiation. But Trump wants military options, too, and the Pentagon is working hard to deliver them. Dunford must be prepared for a possible North Korean nuclear-missile launch, anytime.

John Hamre, a former deputy secretary of defense, recently cautioned colleagues at the Center for Strategic and International Studies, which he heads, that a high-level administration official had admonished him that “we are running out of time on North Korea.” To which Hamre responded: “What the hell are you talking about? … Everyone in Washington should just calm down. Stop working ourselves up to a fevered pitch with breathless rhetoric that has no policy direction. We have lived with this before and we will live with it now.”

Will Mattis offer similar patient counsel, born of his experience as a battlefield commander? Will a new secretary of state be as effective a partner for Mattis as Tillerson has been? Can Mattis remain so widely respected, among Republicans and Democrats, without drawing the wrath of a peevish, prideful president? Those are some of the Pentagon puzzles for 2018.

Mattis has been reckoned as a force for calm, but it may be that the storm is only just beginning.

— David Ignatius is a columnist for Washington Post Writers Group.