A radical islamic insurgency named Alshabab has appeared in Somalia in recent years. African Union forces, with the support of the international community are actively engaged to defeat this movement. The African Union Mission in Somalia (AMISOM), composed of nine thousand troops from Uganda and Burundi, is confronting Alshabab, alongside the Transitional Federal Government's (TFG) forces. On October 2011, Kenya also launched a military campaign into Somalia to defeat the radical group. The research question is to investigate the emergence of Alshabab in Somalia. This movement has adopted a jihadist ideology as well as terror methods. The collapse of the Somali State, two decades ago and a number of factors, both internal and external, could explain the spread of the radical ideology in Somalia. These factors could also explain the predominance of Alshabab over other armed factions. However, due to its radicalism and its uncompromising stance on politics, Alshabab is becoming isolated. Nevertheless, the movement is benefitting from the division of its opponents and the total defeat of Alshabab with an exclusive military approach is unlikely to succeed.