Garrett M. Graff is the author, most recently, of "Raven Rock: The Story of the U.S. Government's Secret Plan to Save Itself—While the Rest of Us Die."

Daniel Ellsberg — best known for the revelation of the Pentagon Papers — opens his new book with a bold and exciting premise: When he copied that groundbreaking Vietnam-era study, which upended the Nixon administration and ultimately transformed Ellsberg into the first whistleblower cause celebre, he also copied thousands of other documents from the 1950s and 1960s concerning the nation's nuclear war plans that he had intended to release as well. "I copied everything in the Top Secret safe in my office [at the Rand Corporation] — of which the seven thousand pages of the Pentagon Papers were only a fraction," he explains. His intention to release the other documents was a secret he kept "from the time of my copying until now."

For a few pages it seems like his book, "The Doomsday Machine: Confessions of a Nuclear War Planner," might boldly blow open the doors on a culture of mystical secrecy that has pervaded the nation's nuclear apparatus for seven decades.

But then Ellsberg reveals that the papers were put in a green garbage bag during his Nixon-era legal battle and were buried for safekeeping by his brother, Harry, at a marked location in a trash dump. A summer hurricane destroyed the marker, and the papers have been lost forever, despite many weekends of "heroic" digging by his brother.

Thus, instead of a new, groundbreaking leak, Ellsberg offers what amounts to a travelogue of what he calls the "Doomsday Machine," the systematized procedures, protocols and strategies that guided how the country's nuclear weapons would be fired if Armageddon arrived — most of which remain in place to this day. The book's exposés, such as they are, offer for historians not much that is new or revelatory, but casual readers will probably be shocked by just how boneheaded and illogical much of the Cold War's grand strategy really was. Yet Ellsberg's book, perhaps the most personal memoir yet from a Cold Warrior, fills an important void by providing firsthand testimony about the nuclear insanity that gripped a generation of policymakers.

"The Doomsday Machine" is not Ellsberg's first memoir. Fifteen years ago, he published "Secrets," chronicling his career and experience with the Pentagon Papers. Many of his most fascinating stories and his conclusions about the nuclear era first appeared there, sometimes repeated almost word for word in "The Doomsday Machine." Both memoirs share a similar arc: the tale of a man gradually deducing that all the strategic tenets he had been taught to embrace were, in fact, political theater at best and lies at worst. It's a sad commentary on life in bureaucratic Washington that so many national security memoirs feature protagonists who express — and expose — grave misgivings about the policies they helped implement or execute, yet who felt powerless in the moment to change direction.

Ellsberg spends much of the book outlining his urgent, at times desperate, efforts inside Washington to explain just how off the rails the Cold War had gone — to capture the attention of top leaders and educate them on how the routine war plans in their file cabinets and briefcases were really blueprints for the effective extinction of modern life, an earth-shattering apocalypse that would kill hundreds of millions more people than realized. His story is peppered with his encounters of major historical figures such as Gen. Curtis LeMay and Robert F. Kennedy. Yet, from history's arc, we know his efforts made little difference.

His journey through our nation's nuclear apparatus goes from remote military bases in Korea and on the shores of Japan to the sun-drenched life of a Rand analyst in California and to the halls of the Pentagon and the White House. At every stage he became further convinced that policymakers did not fully understand the sheer madness that pervaded the deployment and strategy of nuclear weapons. It was an era when our technology for killing far outstripped our technology for communication, forcing front-line military leaders to improvise nuclear procedures when radios fell silent because of routine and entirely predictable — even daily — atmospheric interference. Such blackout periods could have left far-flung field commanders or even individual pilots to decide whether to embark on a nuclear holocaust.

Even as policymakers in Washington believed that presidential authorization for nuclear weapons was the law of the land, Ellsberg realized that the president's nuclear football was "essentially a hoax." In reality, certain military commanders had received pre-authorizations that allowed them to decide when, where and how to launch a nuclear attack if they thought they had lost contact with Washington during an emergency or were in imminent danger. But such orders were terribly ambiguous. A "sane and conscientiously loyal commander might have reason to believe that he was authorized to start a nuclear war under not-uncommon circumstances," Ellsberg writes.

That strategic recklessness continued even as weapons made the leap from atomic bombs to thermonuclear ones — an increase in power of a thousand-fold, which transformed casualty estimates from "mere" tens of millions to hundreds of millions or even 1 billion deaths worldwide.

"What I was looking at was not simply an American problem or a superpower problem," Ellsberg writes. "With the age of warring nation-states persisting into the thermonuclear era, it was a species problem."

The biggest problem, Ellsberg explains, is how all of these plans for doomsday were kept so secret during the Cold War that they failed to achieve the intended level of deterrence. Ellsberg dubs this challenge the "Strangelove Paradox," from the famous movie when Dr. Strangelove declares, as the characters realize they are heading inevitably and unavoidably toward Armageddon: "The whole point of the doomsday machine . . . is lost if you keep it a secret! Why didn't you tell the world, eh?!"

Ellsberg's stories underscore the conclusions of other recent Cold War histories such as Eric Schlosser's "Command and Control" and Michael Dobbs's "One Minute to Midnight": that it's a miracle nuclear weapons have not been used since World War II. The world has stumbled much closer, more times, than we ever realized — and nuclear weapons have been a more integral part of geopolitics than we like to remember. Ellsberg recounts more than 25 times that U.S. presidents have threatened a "first strike" attack on countries from the Soviet Union to Vietnam to Iraq — a list, by the way, that doesn't include the current president's recent Twitter taunt that he has a bigger nuclear button than North Korean leader Kim Jong Un.

Ellsberg underscores time and again how secrecy, often unnecessary and self-defeating, pervaded the defense plans — then and now. Indeed, "The Doomsday Machine" is strongest as a portrait of the slow corruption of America's national security state by layer upon layer of secrecy. He relates how the Cold War, the nuclear build-up and trillions of dollars of defense spending were compromised by information purposely withheld from the policymakers and politicians who debated and shaped our path. In one especially troubling story, Ellsberg says he determined that the Joint Chiefs' primary war plan was kept secret from even the secretary of defense, with a prohibition even against mentioning its title, the Joint Strategic Capabilities Plan, to the defense secretary's office.

These secrets within secrets within secrets meant that few decision-makers actually understood the emptiness of Soviet threats — or the stunning military and intelligence superiority that the United States possessed. Ellsberg's colleagues at the Pentagon and Rand thought their top-secret clearances granted them a full understanding of the world's risks, without realizing how little their knowledge reflected reality. Because of that warped perspective, he and his colleagues pushed for ever-larger weapons to combat threats that didn't exist. As he concludes, "Unintentionally, yet inexcusably, we made our country and the world less safe."

And chillingly, he explains, "The basic elements of American readiness for nuclear war remain today what they were almost sixty years ago," with thousands of unnecessary weapons on hair-trigger alert. "The Doomsday Machine," as it is, remains a daily threat to all of us — the question we face is how much longer will our luck hold that it goes unused? Ellsberg argues, "This is not a species to be trusted with nuclear weapons."

The Doomsday Machine

Confessions of a Nuclear War Planner

By Daniel Ellsberg

Bloomsbury. 420 pp. $30