The paper presents the de-classified preliminary findings of the European Commission funded FP7 research project PRIME, dealing with the extremism, radicalization and lone-actor terrorism (also known as “lone wolf terrorism”). The Article provides the results
of the research devoted to the existing counter-measures used against such threats during the stages of Attack Preparation and Attack Execution. Thirteen such Police and Intelligence methods were analysed from the point of view of their effectiveness, ease of use and costs associated with them, from the point of view of the law-enforcement agencies and security services.