Terrorism is a special type of political violence that entails the deliberate use or threat of extreme violence to create a climate of fear. It is important to recognise that there are many types of terrorism. Historically the most lethal and destructive has been state or regime terror. Terrorism becomes truly transnational when it crosses the borders of numerous states. Hence, counterterrorism has to deal simultaneously with ‘traditional’ terrorist groups, the major challenge of the Al Qaeda movement and its network, and newly emerging groups. The Internet is undoubtedly now the most significant channel for Al Qaeda radicalisation and recruitment. For many reasons, a holistic multi-pronged approach which develops much closer and more effective international cooperation is vital.