Like the rest of those living in New Orleans at the time, Aaron Miller – then the city’s homeland security director – was terrified after a gunman drove a truck into a crowd celebrating Bastille Day in the French coastal city of Nice in 2016, killing 86 people and wounding many more in a terrorist attack claimed by the Islamic State (IS).
Similar car attacks in Berlin, London, New York and Barcelona also put him on edge as he thought about the safety of his city.
