The departure of fighters from Europe to war-torn countries in the Middle East is a serious problem facing modern society. Primarily, it signifies the strengthening of terrorist organizations in the Middle East, which they ultimately join, of which sixty are known so far. Second, it shows a clear picture of the problem of radicalization and its prevalence in Europe. The channels through which radicalization is carried out indicate the presence of followers of terrorism in the West in society, religious institutions, prisons as well as on the vastness of the Internet. If today's situation does not dwell only on the problem of departure, Europe was also faced with the problem of the return of foreign fighters who want to return to their home countries, never more strongly than after the fall of the caliphate. The return of foreign fighters is not something that is completely new and unknown, but while it used to be about isolated cases disappointed by the situation that awaited them in the 'jihadi world', now it is about a large number of returnees who want to leave the inhumane conditions in the Syrian camps. In addition to foreign terrorism, there is also a great danger from domestic terrorism, and the national security responses that are expected from all European countries, especially the member states of the European Union, which have so far functioned very well within the framework of the umbrella European Union in other matters, must be of high quality and adequate.