Eighty years after the first and only time nuclear weapons have been used – the US bombings of Hiroshima and Nagasaki in August 1945 – the risk of the unthinkable happening again has never been greater.

The world’s largest nuclear powers – Russia and the United States – are as close as they’ve been to conflict since the height of the Cold War.

As they upgrade their nuclear capabilities, even talking openly about using them, all signs point to the beginnings of a second nuclear arms race.

Only this time, there aren’t just two players, but three: China, once a junior member of the nuclear club, is expanding its arsenal faster than any other nation.