Russia’s Invasion of Ukraine and Its Impact on Japan-South Korea Security Cooperation .......... 191

The Russian invasion of Ukraine on February 24, 2022, marked a significant turning point in international relations, initially perceived as a regional conflict but quickly revealing broader implications for global power dynamics. Western powers promptly supported Ukraine and imposed sanctions on Russia, while new alliances formed, with some states backing Ukraine and others supporting Russia. This shift in the international system led to increased aggression among certain states. Over two years into the conflict, the world remains divided, and the full global consequences are yet to be determined. For Japan and the Republic of Korea (ROK), the invasion underscored potential impacts on East Asia’s security, particularly concerning China’s strategy towards Taiwan, and North Korea’s military ambitions. This realization fostered a rapprochement between Japan and the ROK, overcoming historical tensions to address shared security concerns. The invasion, coupled with political changes in South Korea, catalyzed a new era in Tokyo-Seoul relations. This paper posits that the altered international system due to the invasion was pivotal in reshaping Japan-ROK relations, a claim supported by analysis of official documents and statements from political leaders.