Role conceptions and alliances: explaining U.S. Asia-Pacific allies' policy alignment with the United States over the South China Sea

Abstract

Despite having close military ties with the United States (U.S.) and presumed accommodation of its policies, U.S. allies in the Asia-Pacific region have responded differently to the competing issues between the United States and China. Why are some allies more likely to align with the United States than others in the context of great power competition? The existing literature, which concentrates solely on realism or liberalism, falls short in comprehensively explaining the diverse behaviours of these actors, especially concerning security matters like those related to the South China Sea.

This thesis aims to develop ideational arguments that combine role theory and alliance politics to shed light on the factors that shape the responses of U.S. Asia-Pacific allies to the strategic competition between the United States and China in the region. It seeks to answer two questions: 1) Why do U.S. allies align differently with the United States on regional issues, and 2) when is a regional ally more likely to align with the United States? By applying role conceptions from role theory to alliance politics, I propose a “role conception balancing framework.” The central claim is that for a U.S. Asia-Pacific ally, the interaction between its role as an ally and its role in a specific policy field (issue-based role) impacts its level of alignment with the U.S. in this particular area when the United States is competing with others. In this setting, the U.S. ally role of a regional state determines the country’s intention to follow the United States, but its issue-based role could limit its willingness to display policy positions in this area.

I employ structured, focused comparison case studies and discourse analysis to investigate four U.S. regional allies, Japan, South Korea, Australia, and Thailand, in relation to their responses to the South China Sea issue between 2009 and 2019. Based on primary and secondary sources, including official documents, high-ranking officials’ remarks, publicised databases, and interviews with policy analysts and scholars, this study conducts cross-national controlled comparisons that assess the most similar cases following the “congruence method.”

The empirical evidence validates the conceptual framework. It finds that a regional ally with a stronger ally role conception is more likely to follow U.S. policy. However, its role in specific policy areas also matters. The active agent is more likely than the inactive agent to take positions on this issue when their U.S. ally roles are equal, despite the fact that such positions may anger China. An ally can only demonstrate a high level of alignment with the United States on an issue if it plays both a stronger U.S. ally role and an active agent role. In a situation where the country is both a weaker ally and an inactive agent at the same time, it shows a low level of alignment with the United States. This challenges the conventional wisdom that weaker allies naturally accommodate their stronger partners within military alliance systems, particularly over security issues; in addition, it offers a different perspective in understanding the divergent behaviour of these weaker allies. The conceptual framework may be extended beyond the timeframe and could include other U.S. allies and policy areas in future studies.