A few weeks ago, as grim news tumbled out of Syria, I travelled to a pleasant American holiday resort to participate in a conference of (mostly western) political and corporate leaders. Unsurprisingly, geopolitics topped the agenda: for hours delegates debated the Middle East, the antics of the Russian president, Vladimir Putin, and the health of China. As the night drew on, the crowd flopped on to sofas with popcorn for “light” entertainment: a screening of Steven Spielberg’s new cold war thriller Bridge of Spies.

It tells the story of an American lawyer, James Donovan, who improbably orchestrated a deal in 1962 to swap a captured Russian spy for two US prisoners, including Gary Powers, the U2 spy-plane pilot captured by the Soviets. It was entertaining and also pretty accurate — according to some of the military leaders who were, somewhat surreally, sitting on the sofa that night.

Watching the film, I felt a sense of regret — although not for reasons the producers might expect. In the early 1960s the world was gripped by fear: people in the USSR and the US both knew that nuclear bombs could wipe out their nations.