Thailand’s role in the context of ACMECS centrality: (re)constructing the Mekong’s regional architecture

This study examines Thailand’s move to advance the Ayeyawady–Chao Phraya–Mekong Economic Cooperation Strategy (ACMECS) within the existing institutional arrangements of the Mekong region, which collectively constitute an unfinished regional architecture, and takes this move as its case study. Utilising a case-study approach, which emphasises a close reading of the specific case, the research design broadly applies political realism—focusing on autonomy, independence, and relative gains—as an analytical lens for screening, interpretation, and contextualisation. The findings indicate that Thailand’s strategic calculations stem from internal determinants, such as the policy transfer back to the Ministry of Foreign Affairs after the 2014 coup, and external determinants, particularly the rapid involvement of China since 2014 through the establishment of the Lancang–Mekong Cooperation (LMC). China’s efforts to launch LMC sectoral bodies seek to reduce the political relevance of existing institutional arrangements; consequently, constructing ACMECS centrality may be viewed as a counterbalance to Chinese efforts to establish a Sinocentric order. Although strategically expedient, promoting ACMECS centrality could have unintended negative implications and requires sustained political will and support from both the Mekong nations and external powers.