Defence Integration between the Russian Federation and the Republic of Belarus (1992–2023): Legal Foundations, Military Mechanisms, and Implications for European Security

This article provides a comprehensive analysis of the evolution of Russian–Belarusian defence cooperation from 1992 to 2023, situating it at the intersection of international security law and strategic studies. It reconstructs the legal–institutional framework underpinning integration, beginning with bilateral agreements in the early 1990s, expanding through the 1997 Union Treaty and 1999/2000 Union State Treaty, and consolidated by post-2017 implementation acts. The study demonstrates how declaratory commitments have been transformed into operational mechanisms, particularly through the Regional Grouping of Forces (RGF), joint planning, coordinated procurement, border management, and the legal status of Russian facilities on Belarusian territory. By linking treaty obligations to observable military practices, the article develops a sovereignty-sensitive framework that evaluates Belarus’s constrained autonomy in procurement, basing, and command authority. It also assesses the implications for NATO’s eastern flank, highlighting reduced warning times, expanded Russian strategic depth, and the compression of operational timelines in the Suwałki corridor and adjacent sectors. The findings underscore how defence integration has become legally entrenched, operationally resilient, and asymmetrically structured, while simultaneously framed by Minsk and Moscow as defensive and stabilising within the Union State’s security concept.