The Russia–Ukraine war, reignited by the 2022 invasion, represents a major turning point in post-Cold War European security. Beyond the battlefield, it has intensified debates over NATO’s role, redefined EU defense and energy policies, and accelerated global realignments. The conflict is marked by hybrid warfare, sanctions regimes, contested narratives, and shifting alliances — making it a key case for studying contemporary power politics and the evolving rules-based international order.