In 1969, Daniel Ellsberg made copies of top-secret documents, held in his safe, which became the Pentagon Papers.
Publication of the leaked papers revealed how much US administrations had withheld from or lied to the public over the Vietnam War.
But Ellsberg, then a military analyst employed by the Rand Corporation and working for the defence department, copied much more – another 7000 pages or so of his notes, estimates and studies on planning for full-scale nuclear war.
His book, The Doomsday Machine, Confessions of a Nuclear War Planner draws on his inside knowledge to expose a history of nuclear ambition, capability, and intention.
Ellsberg sums up America’s 70-year-long nuclear war policy as "mad, insane, and criminal”.
Ellsberg, now 86, says if the nuclear plans had been carried out, 99 percent of humanity would be extinguished.
“Those are the plans which essentially exist today in the US and Russia,” he says.
In 1961 he drafted top secret guidance issued by Defense Secretary Robert McNamara to the Joint Chiefs of Staff on operational plans for a general nuclear war.
“The knowledge was very closely held by the military, and even within the military” and withheld from the president and any politicians.
The military had calculated 600 million people would be killed if the nuclear attacks had been carried out; “a hundred holocausts,” he says. Horrendous as that number is, Ellsberg says it was a gross underestimate, failing to take into account the effect of firestorms and a years-long nuclear winter, which would result in mass starvation.
“It seemed to be the most evil and insane plan that ever existed.
“Nothing could justify planning of this nature.”
Though many more civilians are involved in planning now than in the 1960s, and much more is known publicly, nothing much has changed, he says.
The plans are “as crazy as they were then”.
“The kind of civilians that get access to this material and work on it, in general, have not been that distinguishable from the military.”
Ellsberg lists 25 occasions between 1945 and 1996 when US presidents either threatened enemies with nuclear weapons or secretly considered firing them.
Nuclear weapons are being continuously used, as a deterrent: “The way you point a gun – if you get your way without pulling the trigger that’s the best use of the gun.”
He’s looked at the circumstances of these uses, and of false alarms in which the US and Russia were preparing to launch missiles.
“When I see how much that’s happened and the actual circumstances I have to regard it as something of a miracle that the trigger hasn’t been pulled.
“It doesn’t give me reassurance; had the trigger been pulled in a way that led to all-out war with the US and Russia we wouldn’t be here.
“People who think there was no chance that a nuclear war would come, say, from a false alarm or from an accident or from an unauthorised action just don’t know the system.
“There is a chance - and it remains a real chance.”
While total denuclearisation in the short or mid term is unlikely, it’s still possible to eliminate the risk of nuclear winter, by getting rid of the “doomsday machine”of large numbers of weapons on hair-trigger alert.
Ellsberg says North Korea, with its 10-20 operational nuclear weapons is capable of causing casualties in the millions, but that number of weapons is “not a danger of extinguishing life on earth.”
“If other countries came down from their hundreds or in our case thousands of weapons, on hair-trigger alert in the US and Russia case,… if you get rid of those ICBMs even on one side, the chance of a nuclear winter is very much lowered.
“We can make this world far safer than it is, even without coming to the point of zero nuclear weapons – which should indeed be the ultimate goal.
The prospect of talks between North Korean leader Kim Jong-un and US President Donald Trump was “inconceivable to me … a week ago” he says.
“New sunlight has come through the clouds on that one … with the possibility of real negotiations of a kind that should be occurring with all the nuclear states, and above all with the US and Russia.”