This study aims to explore the shifting power of political and security actors in Europe after Brexit and the war in Ukraine, examining its consequences for European security and its implication for the Asia Pacific region. Changes in the geopolitical and security dynamics in Europe can affect the roles played by countries in the region, leading to previously less influential countries becoming more important and significant in certain context.  Initial research shows that shifting power of political and security actors in Europe is complex and dynamic process that does not happen suddenly. The roles of actors can change over time and according to global, regional and national political condition and circumstances. Brexit and the War in Ukraine are considered two of the most significant driving factors of the shifting power of European actors, although there are other driving factors such as the rise of the rightist and leftist nationalist movements, economic crisis, immigration crisis, the strengthening of Russia’s influences through the energy sector, and China’s investment penetration in Europe. Political and security actors in Europe include not only countries such as Germany, France and the UK, but also regional institutions such as EU and NATO. There are four pulling factors that contribute to the shifting of political and security power of these actors, including political and economic crisis, shifts in political preferences in society, change in a country’s national strategy, and global influences. This study uses a qualitative method with a multidisciplinary approach that includes geopolitical analysis, security analysis, and international politics. The study will conduct a hierarchical analysis using Power Transition Theory, Actor Centered Institutionalism, and Regional Security Complex Theory (RSCT). The findings of the initial research show that the shifting power of political and security actors generally occurs due to the changes in the balance of power between countries in a particular region.

Keywords: European actors, regional security, Asia Pacific, power transition theory, actor-centered institutionalism, and regional security complex theory (RSCT).