In March 1939, flashes on an oscilloscope convinced physicist Leo Szilard that neutrons were emitted in the fission process of uranium and that harnessing nuclear energy was "around the corner."

Believing fervently that any means should be used to defeat the Nazis, Szilard persuaded Albert Einstein to urge President Franklin Roosevelt to initiate what became the Manhattan Project. He sensed as well, however, that "the world was headed for grief."

In 1945, President Harry Truman ordered his armed forces to drop nuclear bombs on Hiroshima and Nagasaki. Many Americans maintain that these weapons shortened World War II and saved the lives of hundreds of thousands of soldiers. Many maintain as well that the existence of nuclear arsenals deterred leaders of the United States and the Soviet Union from starting World War III.

Daniel Ellsberg, the whistleblower who leaked the Pentagon Papers to the media in 1971, insists that targeting noncombatants (whether or not war has been declared) constitutes an act of terrorism. Drawing on his work as a consultant to the Defense Department and the White House in the 1950s and '60s, Ellsberg also contends in "The Doomsday Machine" that policies governing the use of nuclear weapons by the United States have been — and remain — reckless and insane. His book is chilling, compelling and certain to be controversial.

Responding to the likelihood that Soviets would try to "decapitate" the president of the United States to prevent him from ordering a nuclear attack, Ellsberg reveals, Dwight Eisenhower and his successors secretly delegated launch authority to the Secretary of Defense, a handful of four-star admirals and generals, and "commanders in the field thousands of miles from Washington." The same system is in place in Russia. And both superpowers now have "doomsday machines" designed to automatically release ICBMs when they detect, for example, near-simultaneous explosions in several cities.

Ellsberg also documents how close the world has come to a nuclear Armageddon. During the Cuban missile crisis, he indicates, a Soviet officer, who was under orders not to fire at U.S. aircraft without authorization from his commander-in-chief, acted on his own when he suspected an invasion of the island was underway. On a Soviet submarine, where at least two officers were required to agree on firing their "special weapon," the captain and political officer gave the go-ahead, but were overruled by the chief of staff of the brigade, who happened to be on this vessel.

What was true of the Cuban missile crisis, when leaders were "as responsible, humane, and cautious as any we have seen," Ellsberg emphasizes, is even more true today, posing "intolerable dangers to the survival of civilization."

Ellsberg recognizes that it is "entirely quixotic" to expect the present president or Congress to announce a "no first-use" policy; the elimination of ICBMs and doomsday machines; and a probing investigation of war plans in light of a "nuclear winter." But who can blame him for warning us, as the Rev. Martin Luther King did about Vietnam, that "there is such a thing as being too late."

Glenn C. Altschuler is the Thomas and Dorothy Litwin Professor of American Studies at Cornell University.