The journey of an American 'cold warrior' from nuclear deterrence to nuclear disarmament. Former US Secretary of Defence William J Perry has spent his entire seven-decade career on the nuclear brink. A brilliant mathematician, he became involved in the development of weapons-related technology in the aftermath of World War II. As an analyst working at the heart of the Cuban Missile Crisis, he thought each day could be "my last day on earth." He was undersecretary for defence under President Carter in the 1970s, and secretary for defence under President Clinton in the 1990s. He arranged the dismantling of thousands of nuclear weapons in former Soviet republics after the collapse of the USSR, used strategic diplomacy with nuclear nations to prevent escalation, and argued - unsuccessfully - against the NATO expansion that Russia continues to find so threatening.

Now Secretary Perry is worried. Very worried. President Trump and President Putin are both ramping up their bellicose rhetoric. Mr Perry sees an increasing risk of nuclear conflagration in South Asia and the Korean peninsula, and in the face of an on-going terrorism threat, he is concerned unsecured nuclear materials could fall into the wrong hands.

"Today, the danger of some sort of nuclear catastrophe is greater than it was during the Cold War and most people are blissfully unaware of this danger," he argues.

What can be done? In a challenging interview with Edward Stourton, Secretary Perry reflects on the nuclear nightmare, and lays out his formula for nuclear security in our changing world.

Producer: Linda Pressly

(Image: Dr William Perry gives a lecture at Stanford University about the history of nuclear weapons. Credit: Light at 11b).