A single nuclear weapon could destroy America’s entire electrical grid, claims a former head of the CIA. The explosion would send out an electromagnetic pulse – resulting in famine, societal collapse and what one newspaper has called a “Dark Apocalypse”. But are hungry squirrels a greater threat to the electrical grid than North Korean weapons? We speak to senior security adviser Sharon Burke and Yoni Applebaum from The Atlantic. Presenter: Charlotte McDonald Producer: Hannah Sander