Radicalization encompasses many issues which mandate those who are responsible for countering it to have a multi-faceted approach. Three main sources of complexity in radicalization include 1) the definition of the concept of radicalization, 2) process, through which individual becomes a member of a terrorist organization, 3) counter-radicalization strategies, which has two folds; prevention and de-radicalization. The only way to have effective and result-oriented countering radicalization strategy is to comprehend this complexity, which requires joint effort at the national, regional and international level.