A theory of alliance restructuring the cases in East Asia, 1946 - 2000

Why do some allies restructure their existing alliance relationships which they once favored, but some do not? In what ways do allies restructure their alliances? Historically interstate military alliances change their original agreements more than they remain the same, and the average duration of bilateral alliances is less than a decade. Theoretically, previous works have paid great attention mostly to the formation and duration of alliances. Answers to the above basic questions have been largely indeterminate, despite the fact that when allies change their original agreements, it reshapes the behaviors of both allies and non-allies. This study argues that when a state grows more powerful relative to its neighbors and external powers; and experiences a domestic regime change, the state is likely to restructure its exiting alliance relationship. These external and internal changes since the alliance formation cause the state's original preference on the arms-and-allies balance to shift, and the state has greater incentive to restructure the existing alliance by way of dealignment, expiration, or renewal.;In order to test the argument, this study first provides the quantitative results by testing 142 post-WWII alliances formed from 1946 to 2000, and identifies the statistically significant and substantial effects of three factors, capabilities increase, regime change (democratization and authoritarianization), and government change (both leadership and supporting coalition change), on the state's alliance restructuring. Then this study qualitatively tests the quantitative findings and traces the causal process through case studies for three U.S. alliances in East Asia (the Philippines, South Korea, and Japan). The Philippine alliance restructuring in 1992 is examined as a typical case demonstrating that the argument empirically works. Then this study investigates why South Korea did not restructure the alliance with the U.S. in the 1990s even though the external and internal factors suggest that it would restructure. Lastly, the U.S.-Japan alliance case in 2009-2010 is examined to assess the explanatory power of the argument beyond the data population. An alliance restructuring can significantly affect an individual state's security positively or negatively, therefore state leaders must continue to pay a close attention to the management of alliances.