This weekend marks the 100th anniversary of the end of the First World War, one of the world’s most horrific conflicts. One of the best accounts of how this tragedy began, by the historian Christopher Clark, details how a group of well-meaning European leaders – “The Sleepwalkers” – led their nations into a war with 40 million military and civilian casualties. Today, we face similar risks of mutual misunderstandings and unintended signals, compounded by the potential for the use of nuclear weapons – where millions could be killed in minutes rather than over four years of protracted trench warfare. Do we have the tools to prevent an incident turning into unimaginable catastrophe?