Сучасна воєнна дипломатія в дії: міжнародно-правовий контекст відносин між Україною та Європейським Союзом

Against the backdrop of today’s complex geopolitical realities, the world is experiencing a state of heightened turbulence, which gives rise to new challenges and threats to the international security system. Following the end of the unipolar era, a polycentric world order has emerged, characterized by intensifying competition among multiple centres of political, economic, and strategic influence. This competition increasingly takes on a confrontational nature, marked by hybrid confrontations, economic coercion, information warfare, and localized armed conflicts. There is growing concern about the risk of escalation in regional conflicts – in Eastern Europe, the Middle East, Southeast Asia, and the Indo-Pacific – which could potentially develop into wider global confrontations. At the same time, the spread of authoritarian tendencies, the weakening of international legal institutions, the crisis of multilateral mechanisms for conflict resolution, and the intensifying struggle for resources further deepen global instability. Under current geopolitical turbulence, wartime diplomacy acquires a new functional and legal dimension and becomes a decisive tool for safeguarding national interests and ensuring compliance with international law. Modern wartime diplomacy functions as an adaptive legal-political mechanism operating under heightened security pressures and emergency legal regimes. Its effectiveness increasingly depends on the state’s ability to combine classical diplomatic means with security-oriented, sanctions-based, and institutional instruments of influence. This study examines the international legal foundations of such diplomacy and demonstrates that Ukraine’s wartime practice has catalysed the transformation of external action mechanisms in response to contemporary threats. The research shows that wartime diplomacy operates within a distinct legal framework shaped by the interaction of international humanitarian law, international security law, and the evolving system of European Union (hereinafter – EU) external action. Rooted in the general principles of international law and treaty-based solidarity mechanisms, it performs not only a political but also a juridical function by institutionalising emergency foreign policy decisions. Based on Ukraine’s bilateral and multilateral cooperation formats, it becomes evident that wartime diplomacy delivers not only declarations of support but also tangible legal and political shifts. Existing instruments of cooperation have evolved into long-term and more structured forms of security partnership, approaching the logic of a quasi-alliance. At the same time, new legal avenues of accountability for aggression are emerging, reinforcing Ukraine’s protection in the international arena. As a result, Ukraine is no longer merely a recipient of assistance but an active subject of international law, while the EU increasingly moves from being primarily a “normative power” toward acting as an actor of collective security in the context of armed conflict.