Purpose. To investigate the genesis and key historical aspects that have led to the popularization of the concept of “definlandization” in scientific literature, as well as the strategic priorities of the formation of the Marshall Plan within the framework of a possible military and economic union between Great Britain, Ukraine, Poland and the Baltic countries. To propose optimal ways of neutralizing economic threats and to determine probable scenarios of the post-war reconstruction of the infrastructure of the national economy of Ukraine. Methodology. The article uses a combination of correlation and SWOT analysis, which made it possible to calculate the value of natural wealth in the post-war period based on SPSS Data Analysis Software. The used economic-mathematical methods made it possible to form an algorithm for calculating the cost of restoring Ukraine’s total resource losses from Russian aggression in monetary terms and to establish mutually unambiguous correlations with the value of gold using Pearson criterion. Findings. The authors’ spectrum of factors influencing the New Economic Policy in the post-war period has been systemized to determine the estimated amount of necessary resources for the post-war restart of the national economy of Ukraine. For the first time, the need to abandon the Finlandization policy has been scientifically proven, as domestic resources and funds from reparations will not be sufficient for the sustainable development of Ukraine. It was established that the main guarantee of investing in the Ukrainian economy is the high value of natural resources in all regions of Ukraine, which is estimated in monetary terms at approximately 4 trillion hryvnias and the innovative architecture for the “Marshall Plan” of the post-war reconstruction of the infrastructure of Ukraine is given. Originality. The used analytical-mathematical methods made it possible to establish correlations in the regional distribution of the value of natural wealth. In contrast to existing studies, this article not only objectively determined the number of losses in monetary terms but also proposed specific ways of their compensation in the context of the formation of a new economic policy of definlandization of Ukraine on the basis of economic and mathematical modelling of a typical scenario of recovery of the national economy. Practical value. The conducted study on potential ways of definlandization of the national economy was provided for study at the Ukraine Recovery Conference (URC 2022, Lugano, Switzerland). In particular, the authors of the report justified the economic feasibility of moving European production facilities (Robert Bosch GmbH, Siemens, Schneider Electric, SKF, Renault, BMW Group, Mercedes-Benz, Volkswagen, Volvo Group, etc.) from the territory of the Russian Federation, which would facilitate the remigration of Ukrainians and accelerated development of Ukraine based on the principles of decentralization, subsidiarity and definlandization.