Due to Greece's geographical position and socio-political background, the country is at the heart of the migration phenomenon. As such, Refugee Crisis: Global Perspectives, Challenges and Issues first reviews the new technologies by which the borders of Greece are secured. The authors study and analyze the phenomenon of irregular immigration, particularly with respect to its causes and potential security issues. Continuing, this compilation seeks to determine the diversity of Estonian-language and Russian-language discourses in the context of immigration-related issues, questioning whether the refugee crisis has influenced the political identities of the dominant majority and the Russian-speaking minority in Estonia. The collaborative projects of UNHCR-Pakistan related to Afghan refugee children's education in Pakistan are explored, aiming to assess the actions that have been taken by Pakistan for Afghan refugees. The refugee migration from Syria has been called the humanitarian crisis of our time. In closing, after examining other System Dynamics models that relate to the refugee crisis, the authors build a model to incorporate a sub-model of the Syrian civil war, along with a sub-model of the movement of refugees and their eventual immigration.