About four per cent of US UAV operators have developed post-traumatic stress disorder, which some have attributed to the fact that powerful cameras show close-up footage of the targets of drone strikes after they have been killed. 'The cameras are good,’ Oz says. 'A Hellfire missile does have significant effects on the human body, and you should get to see that. If you can’t accept it, you are in the wrong job. But the weirdest thing for me – with my background [as a fast-jet pilot] – is the concept of getting up in the morning, driving my kids to school and killing people. That does take a bit of getting used to. For the young guys or the newer guys, that can be an eye opener.’