The authors propose an approach to researching criminal policy in the sphere of ensuring national security based on taking into account modern trends within the classical approach. The main part of the work contains an analysis of research aimed at establishing the correlation between the used concepts. The authors have analyzed legislative initiatives aimed at forming a legal understanding of the core of national security. They present some material regarding the comparative characteristics of legislative approaches to determining the basic concepts constituting the object of the study, which were included in the current and the previous Strategies of National Security. It is concluded that there are conceptual contradictions in the official and the scientific positions on determining the essence of the foundations of criminal policy of ensuring national security. Two system-forming structural elements of criminal policy in this sphere are singled out - provision of migration and environmental security. Contemporary trends in the condition, structure and dynamics of crimes committed by foreign citizens and environmental crimes are presented for the period of 2015-2021. It is established that the official methodologies of registering the identified facts of violating criminal legislation in the spheres of ensuring migration and environmental security suffer from common problems because a considerable share of crimes remains unregistered. While there is a general trend for declining rates of registered environmental and migration crimes, the authors stress that high levels of latency and the corruption component are significant features of analyzed phenomena which determine their contents. They conclude that, in order to obtain a realistic picture of the situation, it is necessary and inevitable that a combination of official crime registration methodologies and research approaches should be used to study the abovementioned types of crimes. At the same time, the drawbacks of this approach are also pointed out, primarily, its subjective character and absence of consistency. The authors note the dependence of environmental crimes on migrant crimes and their immediate connection in a certain sphere as they need to be studied together as inseparable elements of a single process of ensuring national security and minimizing modern challenges and threats. The authors also present a way of researching the discussed phenomena in their interrelation alongside a classic approach which emphasizes their independence.