During the Cold War the then US Defence Chief William Perry received a late night call saying 170 intercontinental ballistic missiles had been launched from Soviet territory. The President should be woken to confirm a protocol response. Thankfully a technician quickly realised a training simulation tape had accidentally been triggered. No actual missiles were incoming and no nuclear response would be required that day. One can only imagine the consequences had the error taken longer to come to light. Thirty years on the likelihood of nuclear attack has dissipated but in his book ‘The Perfect Weapon’ David Sanger argues that...