This article demonstrates the flaws of EU intelligence agencies the past decade in the field of counterterrorism, in particular regarding Jihadi terrorism. Since 2014 the West European countries fell victim to the violent actions of Islamic State (IS), which has a huge presence on social media, both on the surface web and on the Darknet. The goal is to outline the most important case-studies of Jihadi terrorism that were plotted and carried out by the terrorists and yet, not prevented by the classical intelligence authorities.