Research objectives and hypothesis/research questions:
The article addresses the following research problem: which NATO member states experienced the largest increases in defence spending between 2014 and 2025? The aim of the study is to conduct a multidimensional analysis of changes in defence expenditure levels among individual NATO countries during the 2014-2025 period. Based on the adopted research problem and objectives, the following hypothesis was formulated: the most significant increases in defence spending in military defense expenditures occur among NATO member states located on the Alliance’s Eastern Flank. This trend is likely driven by the increasing perception of security threats resulting from Russia’s annexation of Crimea in 2014 and the subsequent full-scale invasion of Ukraine in 2022, which intensified concerns regarding regional stability, deterrence capabilities, and military preparedness. At the same time, although the relative growth rates may be higher among Eastern Flank countries, the United States is expected to remain the leader in terms of absolute growth in defence expenditures during the analysed period (2014-2025), owing to its global military commitments, strategic role within NATO, and substantially larger economic and defence budget capacity.

Research methods:
The study employed the method of source analysis, supplemented by inferential reasoning techniques. The research process was supported using Microsoft Excel and Statistica AI software, which enabled the processing, organization, and multidimensional analysis of the collected data. Furthermore, defence expenditure patterns are examined comparatively across Eastern Flank and non-Eastern Flank countries, using the onset of the Russia-Ukraine war as a temporal reference point for assessing pre and post war differences.

Main results:
The main findings of the study indicate a clear trend of rapidly increasing defence expenditures among Eastern Flank NATO countries. In 2025, Poland recorded the highest defence spending level, amounting to 4.48% of GDP. This represents a substantial increase compared to 1.86% in 2014 and 2.21% in 2022. Significant growth was also observed in Lithuania, where defence spending increased from 0.88% of GDP in 2014 to 4.00% in 2025, in Latvia from 0.97% to 3.73%, and in Estonia from 1.90% to 3.38%.

Implications for theory and practice:
The results may also prove valuable for the defence industry sector and entities responsible for logistics and security management by identifying directions for future technological and organizational investments. Furthermore, the analysis may support forecasting processes concerning future changes in the defence policies of NATO member states in the context of geopolitical instability and the growing challenges to international security.