Two days after the Jan. 6 Capitol assault, Gen. Mark Milley, chairman of the Joint Chiefs of Staff, placed an urgent call “on a top secret, back-channel line,” to his Chinese counterpart, Gen. Li Zuocheng. This is from Bob Woodward and Robert Costa’s new book, “Peril.” Gen. Milley believed Gen. Li and others in the Chinese leadership had been rattled by what had just happened in America. Gen. Li asked Gen. Milley if the U.S. was politically collapsing. No, Gen. Milley said: “We are 100% steady,” but democracy can seem “sloppy sometimes.”

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Chairman of the Joint Chiefs of Staff Gen. Mark Milley at the Pentagon, Aug. 18.

Photo: Alex Wong/Getty Images

Two days after the Jan. 6 Capitol assault, Gen. Mark Milley, chairman of the Joint Chiefs of Staff, placed an urgent call “on a top secret, back-channel line,” to his Chinese counterpart, Gen. Li Zuocheng. This is from Bob Woodward and Robert Costa’s new book, “Peril.” Gen. Milley believed Gen. Li and others in the Chinese leadership had been rattled by what had just happened in America. Gen. Li asked Gen. Milley if the U.S. was politically collapsing. No, Gen. Milley said: “We are 100% steady,” but democracy can seem “sloppy sometimes.”

It wasn’t their first such conversation. Four days before the 2020 election, according to Messrs. Woodward and Costa, Gen. Milley had called Gen. Li after U.S. intelligence reported the Chinese were on high alert and feared that President Trump, desperate to win, might create a military crisis and present himself as its hero. “We are not going to attack or conduct any kinetic operations against you,” Gen. Milley assured his counterpart. “If we’re going to attack, I’m going to call you ahead of time.” Gen. Li, who’d known Gen. Milley for five years, said he’d take the American at his word.

Soon after the Jan. 8 call, Gen. Milley summoned senior Pentagon officers to his office to discuss the steps involved in a nuclear launch. Only the president could give such an order, but Gen. Milley said he’d have to be involved: “No matter what you’re told, you do the procedure. You do the process. And I’m part of that procedure.”

Since the publication of “Peril,” Gen. Milley has been criticized in some quarters: As head of the Joint Chiefs he’s not in the chain of command. Messages to foreign military leaders should be delivered by civilian officials such as the defense secretary. Who is this guy to take it on himself?

But I see it this way: In a fluid, high-stakes situation, lines of communication are best kept open. Generals of different nations know each other and talk to each other, and it’s good they do. Wars are as likely to start through miscalculation and misunderstanding as bloodlust or reasons of state. The world is preoccupied with ground combat, but this is a nuclear world. Big players, not all of them fully stable, have arsenals. It’s good to establish: No sudden moves.

After Jan. 6, Gen. Milley thought Mr. Trump was mentally deteriorating—manic, scattered, even more unpredictable than usual. Trump supporters say Gen. Milley fundamentally misunderstood Mr. Trump’s nature: His impulses were to end wars, never start them; his moves weren’t martial. True. But Mr. Trump never incited his followers to move with physical force on the U.S. Capitol either, until he did. After that anything seemed possible.

I find myself supportive of Gen. Milley’s actions as described in the book. Yet I come down to a negative view of Gen. Milley after reading it, for two reasons.

One is that it does nothing to enhance America’s position in the world to make it known that the Joint Chiefs chairman found it necessary to call China to tell them Bonkers Man only thinks he’s in charge; if you’ve got a problem, call me. Gen. Milley shouldn’t be talking about all this. He should have kept it to himself, told the next head of the Joint Chiefs and a few historians down the road.

I’ve read the books on the 2020 election and the end of the Trump administration, and Gen. Milley appears to have provided major information in almost all of them. With the caliber of reporters he was dealing with, this would have taken major time—gathering and providing information data, documents and readouts of conversations to substantiate and corroborate his account; interviews, follow-ups, transcripts. The portraits of such a cooperative source would inevitably be driven in a positive direction.

In “I Alone Can Fix It,” by the Washington Post’s Carol D. Leonnig and Philip Rucker, Gen. Milley is decrying systemic racism one day, telling aides that listening to Mr. Trump is like reading Orwell’s “1984” on another. In “Frankly, We Did Win This Election” by the Journal’s Michael C. Bender, Gen. Milley is a street-wise Ivy Leaguer well versed in the Constitution. He instructs Mr. Trump on the nature of the George Floyd protests. “That guy had an insurrection,” he says, pointing to a picture of Lincoln. “What we have, Mr. President, is a protest.” In “Peril,” Gen. Milley constantly saves the republic. He is “burly and ramrod straight,” his shoulders broad, his persona outgoing. Yet there’s a cerebral edge. “One large bookcase in his hallway at Quarters 6 held hundreds of thick books just on China.”

All of it comes across as believable, factually accurate. But one detects a highly enthusiastic primary source.

This is what I thought as I read: Gen. Milley seems to have spent large parts of the past year building the reputation of Mark Milley. (He had marched in fatigues alongside the president at Lafayette Park during the 2020 street protests; he no doubt concluded reputational rehab was in order.) It would have been better if he’d given that time and energy to avoiding the calamitous disaster that was America’s withdrawal from Afghanistan. Instead of seeing to his standing he should have been putting his job on the line to keep Bagram Air Base open.

Top U.S. military officers tend always to have their eye on the media, and how they’re being perceived, which brings us to a larger point. The services are at a hinge point. They have been through 20 years—an entire generation—of war in Afghanistan and Iraq. Now it is officially over. They need to take time to review and reflect on that experience in a kind of service-by-service after-action report. Part of that should include this question: While the wars were being fought, did top brass keep the military a step apart from the damaging cultural and political swirls that have swept the nation?

It looks to me as if they have been too eager to prove they have all the right cultural and political predicates, that they want the media and political class to see this. That they’re desperate for them to see it.

But the U.S. military is the most respected institution in the country in part because its members aren’t like the country. They are understood to have exceptional discipline, rigor, clear and uncompromised standards. They have teamwork and their teams cohere because they have a higher purpose and higher expectations. They are called on to preserve and protect the Constitution. They’ll die for you. They don’t make you swear to that at Oberlin.

If the military doesn’t stay true to its mission, it will become just another institution in a country that carelessly destroys institutions.

The military isn’t a fortress and doesn’t have a drawbridge it can pull up. It comes from us and will reflect us. That’s good. The services should be bringing in everybody—women, sexual minorities—gathering all the talent they can, because only our talent will give us the edge in future wars, which will come. Talent comes from all quarters.

But that doesn’t mean adopting the ideologies and assumptions of the leftist cultural regime that reigns in other institutions—Critical Race Theory, wokeness. Don’t let that stuff in. If in your reviews of the past 20 years you determine you have, stop. Your future and ours depend on it.

Journal Editorial Report: How much of this story should you believe? Images: AFP/Getty Images Composite: Mark Kelly The Wall Street Journal Interactive Edition