During a recent conference in Singapore, someone asked Secretary of Defense James Mattis whether, given President Trump’s withdrawal from the Trans-Pacific Partnership and the Paris climate agreement, we were “present at the destruction” of the America-led postwar order. In a twist on a remark by Abba Eban (often attributed to Churchill), the former general answered: “Bear with us. Once we have exhausted all possible alternatives, the Americans will do the right thing.”

It was vintage Mattis: witty, learned and confident in his country’s future. But it was also dispiriting, suggesting that he disagreed with President Trump, but was unable to do much about it.

We should all be a bit dispirited these days. At the beginning of the administration, most Democrats (myself included), and even a few Republicans, publicly hoped that a cadre of generals and former generals — Mr. Mattis, John Kelly at Homeland Security, Lt. Gen. H. R. McMaster at the National Security Council (who replaced retired Gen. Michael Flynn, a Trump loyalist) — would check Mr. Trump’s worse instincts. On Friday, Mr. Trump moved Mr. Kelly into the White House to serve as his chief of staff, replacing Reince Priebus, asserting that his military background would bring order to a tumultuous executive.