Islands of tension: ASEAN’s engagement with external powers in response to China’s growing assertiveness in the South China Sea

This study analyses how China’s growing assertiveness, specifically the case of militarisation of artificial islands, in the South China Sea (SCS) has influenced the Association of Southeast Asian Nations (ASEAN) engagement with external powers between 2010 – 2024. By examining ASEAN’s strategic behaviour through the lens of alignment theories, this research contributes to a deeper understanding of how regional organisations manage threats and engagement with external powers. The study engages with three competing realist theories: (1) Balance of Power, (2) Balance of Threat, and (3) the Alliance Security Dilemma. Theoretically, it advances the debate on regional alliance adaptability and alliance management under threat. Societally, the findings on ASEAN’s external alignment is relevant for policymakers, diplomats, and security analyst working on alliance dynamics. And even practically, this research gives more insight into the SCS dispute. Methodologically, the thesis uses a congruence analysis approach, systematically testing theory-derived propositions against empirical evidence to assess which framework most convincingly explains ASEAN’s behaviour. The evidence showed that the Alliance Security Dilemma provides the best explanation of ASEAN’s behaviour regarding engagement with external powers. But the evidence points to outcome similarity but does not confirm whether ASEAN’s alignment behaviour is truly motivated by fears of entrapment or abandonment. These findings have implications for the applicability of realist theories on regional organisations and their engagement with external partners. However, further research is needed to understand the underlying motivations behind ASEAN’s behaviour.