It is crucial that governments collect information regarding the incoming flow of immigrants into their countries; this is usually done via intelligence services. Data and information related to migrations is used not only for statistical, humanitarian, medical, public security, and other similar purposes, but are also especially used for purposes concerning national security. In the midst of migrants seeking international help and humanitarian aid, members of organized crime, human, drugs, and weapons traffickers, terrorists, and other criminals/deviants could potentially be hiding amongst those seeking refuge. Their purpose is to clandestinely reaching their destination where criminal offences, terrorism and other similar activities can inflict serious damage to national or international security. During the last few years, the rising inflow of refugees and economic migrants is becoming a more and more serious economic, political and security problem for Europe, especially for the member countries of the European Union. In 2015, the migrant inflow into Europe was above one million, which is the most exceptional influx to date, and policymakers do not have a competent answer of how to react. To make things even worse, Turkey is threatening to push an enormous number of additional migrants into the Greek islands. Additional controversy is present in the Schengen area, which will probably narrow – not expand – the so-called Dublin Declaration, in European countries which are not members of the European Union, in the United Kingdom following Brexit, and in some countries where overall political instability seems incessant. Such political complexity of the given situation in Europe might diminish the capabilities of intelligence and security services that are normally highly successful. The core of the proposed book addresses the statistical analysis and modeling of the potential future of migrant inflow according to Turkey’s possible motives in the future. Since the latter can be quite unpredictable, a relatively difficult forecasting problem is currently unavoidable, and possible uncertainties might be quite severe. The calculated prediction results imply that the migrant inflow trend will remain considerably high, particularly in the case if Turkey decides to completely open its borders for further migrations towards the Greek islands. This finding should be a serious warning to the EU to create a more efficient immigration policy in the near future.