Robert McNamara says he did not realise during the Cuban missile crisis of October 1962 just how close the US and the Soviet Union came to nuclear war. Forty-three years later, the controversial former US defence secretary is more concerned than ever about the dangers of nuclear weapons.

Sitting in his Washington office, the subject of The Fog of War - the Oscar-winning documentary about his views on the Vietnam war - cautions, in a rare interview, that he does not want to talk about Iraq.