Hany Farid, senior adviser to the Counter Extremism Project, agrees. 'They spend huge resources developing technology to find the data about users to target advertising,’ he said. ‘I’m 100% sure that if they put even a fraction of that effort into building an early warning system they could make an impact.’ It takes minutes to find a plethora of terrorist content, including a Facebook page with a recruitment video celebrating the martyrdom of a Canadian jihadi (which Facebook deemed OK when reported). On YouTube it’s easy to find videos of English-speaking Isis fighters calling for American radicals to stab a kafir with a knife, throw him off a building or run him over with a car.