The United States, UK, Israel and now Pakistan all use drone strikes to kill. In September a general in the Pakistani army announced their first ever use of an armed drone. It was directed at a terrorist compound, he said, and killed three. Meanwhile the US is thought to have launched a secret drone campaign to kill so-called Islamic State fighters in Syria.

Armed drones are the counter-terrorism weapon of choice, capable of killing militants from a distance and without putting military personnel in harm’s way. But critics question how far they bolster wider attempts to defeat terrorism. So, do drone strikes work?

(Photo: Reaper flies without pilot. Credit: Getty Images)