Defense Secretary James N. Mattis meets with Saudi Arabia’s First Deputy Prime Minister and Minister of Defense, Crown Prince Mohammed bin Salman bin Abdulaziz at the Pentagon in Washington D.C., 2018. (DoD photo by Navy Mass Communication Specialist 1st Class Kathryn E. Holm)

Secretary Mattis has resigned:

Officials said Mr. Mattis went to the White House on Thursday afternoon with his resignation letter already written, but nonetheless made a last attempt at persuading Mr. Trump to reverse his decision about Syria, which the president announced on Wednesday over the objections of his senior advisers. Mr. Mattis, a retired four-star Marine general, was rebuffed. Returning to the Pentagon, he asked aides to print out 50 copies of his resignation letter and distribute them around the building.

Mattis’ departure from the administration after the midterms had been floated as a possibility for months, but I don’t think anyone seriously expected him to resign suddenly over a policy disagreement with the president. It is telling and not to Mattis’ credit that ending an illegal war in Syria was the one policy disagreement with Trump that Mattis couldn’t stomach. The Defense Secretary had repeatedly disagreed with Trump on a range of issues, and he usually lost the internal debate. The only times that he prevailed with Trump were when he advised him to escalate ongoing U.S. wars, and his influence had waned enough that he couldn’t get his way on that, either. I was extremely skeptical that a Syria withdrawal would actually happen. Now that Mattis has tried and failed to reverse that decision, I have to acknowledge that I overestimated the ability of Trump’s advisers to change his mind.

The Defense Department under Mattis became more opaque and less accountable to the public and Congress. He presided over two years of shameful support for the Saudi coalition war on Yemen, and he went out of his way to offer absurd justifications for continued U.S. support for the war to the end of his tenure. The disagreement over Syria will dominate coverage of Mattis’ resignation, but it is important to remember that when it came to the most indefensible U.S.-backed war he and Trump were always on the same page. No less than Secretary Pompeo, Mattis discredited himself in the desperate, unsuccessful effort to derail S.J.Res. 54. An administration that fights as hard as this has to keep the war on Yemen going is definitely not one interested in peace and restraint no matter what else happens.

As wrong as Mattis was on a number of foreign policy issues, there is a real danger that his successor could be far worse. Even if Trump doesn’t nominate a Tom Cotton or Lindsey Graham, the next Defense Secretary is very likely to be a yes-man in the mold of Mike Pompeo. Almost every time that Trump has replaced his top national security officials, he has chosen someone who will flatter and praise him instead of telling him the truth and giving him the best advice. The next Defense Secretary is less likely to resist Trump’s belligerent tendencies, and he is more likely to indulge the president’s worst impulses. Just as Pompeo has proven to be a worse Secretary of State than Tillerson, Mattis’ successor will very likely prove to be an inferior Secretary of Defense.