In our fast-changing world, nuclear weapons remain a global threat. I'm Edward Sturtin and in this program

Atom Man I'm going to explore nuclear deterrence and disarmament with a Pentagon insider.

The former United States Secretary of Defense

William J Perry. I got just a call in the middle of the night from the

watch officer at the North American Air Defense Command and the first thing he

told me was that his computers

were showing 200 Soviet ICBMs on the way

from the Soviet Union to the United States.

ICBMs or intercontinental ballistic missiles were the biggest beasts in the nuclear arsenal.

William Perry was a senior official at the Pentagon at the time.

He is, as you'll gather from our interview, the most measured of men, but...

For one heart-stopping moment, I thought we were about to see the end of civilization. The watch officer, a general, had a steady nerve.

He quickly went on to say that he had already concluded. It was a false alarm that took us several days to figure out what had happened, which was

that a change of shift, the new computer operating coming in put in a training tape instead of the operating tape in the computer.

And so what was underway was a very realistic simulation of an attack.

Such an easy simple mistake and so much at stake it was a lesson he's never forgotten.

The problem then indeed the problem today with our warning system is that it is susceptible to occasional

errors not often but any one of them could have been enough to have prompted the

president to actually launch our missiles.

Most of William Perry's adult life has been dedicated to planning and building America's

war machine.

He's been in and out of the Department of Defence for decades, rising to the top job there under

...