The divergence of the U.S. alliance solidarity: new relationships with South Korea and Japan after the Cold War

The United States alliance with South Korea and Japan faced new challenges in the post-Cold War period. The recent tendency shows that U.S.-South Korea alliance is weakening while U.S.-Japan alliance strengthened showing divergence in the level of alliance solidarity. This study argues that the domestic politics of the allied state frequently influences the U.S. foreign policy decision-making which affects the level of alliance solidarity. I established two hypotheses which are that based on the public opinion perceptions towards the United States and the government ideology policy line of the allied state, the level of alliance solidarity will be determined by the U.S. government. The findings show that the public opinion and government ideology affects the U.S. government perception. Based on this relationship, the outcome is reflected in the degree of alliance solidarity. As a result, this study provides an alternative explanation of the explanatory factors in determining the alliance solidarity.