This thesis aims to contribute to a deeper understanding of NATO’s evolving partnerships with the Indo-Pacific Four (IP4)—Japan, New Zealand, Australia, and the Republic of Korea—within the context of increasing security tensions in Europe. Russia’s aggression culminated in a full-scale invasion of Ukraine in 2022, the same year the IP4 countries participated in a NATO summit for the first time. At the 2024 Washington Summit, the IP4 attended for the third time, while NATO, for the first time, identified a newly clustered threat from an “axis” of authoritarian states; Russia, China, North Korea, and Iran. This study examines the growing interconnection between the Euro-Atlantic and Indo-Pacific regions through an interpretive process tracing analysis of NATO’s evolving partnerships with the IP4 from 1991 to 2024. Grounded in English school theory, the study applies the concept of primary institutions to explore the normative institutional tensions reshaping international society. The findings highlight tensions among balance of power, great power management, and the values underpinning the rules-based international order.