The Greek security forces cooperate with the Israeli intelligence services to counter terrorist activities on their national territory.

Belgian authorities take continuous measures to counter terrorist activities on their national territory.

Wars, long-term conflicts, the fight against foreign occupations, the feeling of solidarity with the people of the oppressed community are just a few of the factors that have determined, in history, the evolution of the "foreign fighter" phenomenon. Heroes ready to sacrifice themselves for "noble" causes have been on the battlefield since the emergence of nineteenth-century nations in countries like Greece, the United States, Spain, Palestine, Afghanistan, the former Yugoslavia and Somalia (Colgan & Hegghammer, 2011; Hennessy, 2012). But this was only the first stage of the phenomenon.

Compared to other policy fields, the involvement of the European Union (EU) in counter-terrorism is a relatively recent development. Traditionally, European countries faced with a terrorist threat, such as the United Kingdom (UK), Italy, Spain and West Germany, addressed it largely on their own. One of the main reasons for this lack of European cooperation was the commonly held view that each European state was confronted by a distinct threat

In this article, we highlight the need for a multidisciplinary approach, together with the use of complex tools from the EU and the Member States to combat terrorism and the phenomenon of radicalization in prison. Our aim is to identify the main vulnerabilities to the extension of the two phenomena into a universal prison. Our analysis captures the main risks to the post-detention reintegration process, thus emphasizing the need to individualize the instruments and programs of disengagement and de-radicalization. Referring to the EU’s efforts to combat terrorism, we identify the main shortcomings represented by the lack of a unitary, coherent and transnational approach that would facilitate the exchange of information and expertise between Member States.