Small Island Developing States’ Foreign Policy and Regional Organisations: Strategic Differentiation and Post-Exit Re-engagement in the Global Periphery

Small Island Developing States (SIDS) are widely recognised for their structural vulnerabilities, including geographic isolation, limited resources, and high exposure to climate risks. Yet these states frequently exercise considerable geopolitical and geoeconomic agency, not least through their engagement with regional organisations (ROs). This paper examines how SIDS use strategic differentiation, a flexible and pragmatic calibration of participation levels, to manage their regional commitments. Rather than understanding withdrawal from ROs as a rupture, we conceptualise it as one phase within a broader cycle of selective engagement that often culminates in renewed or reinstated participation. Drawing on recent scholarship on differentiation and post-exit dynamics, we analyse two cases characterised by temporary withdrawal followed by re-entry: Kiribati and the Pacific Islands Forum (PIF), and the Seychelles and the Southern African Development Community (SADC). In both cases, withdrawal was not intended to sever regional ties but to signal dissatisfaction, manage domestic constraints, or recalibrate relations within the regional organisation. Their subsequent return to active participation reflected shifting regional conditions, evolving domestic priorities, and the continued value of ROs as platforms for voice, influence, and problem-solving. The paper locates itself within the growing literature that frames withdrawal from an RO as part of an iterative process that transforms rather than terminates regionalism. By analysing how SIDS disengage and subsequently re-engage, the paper highlights the fluidity of membership in regional organisations and shows how small states strategically navigate regionalism through cyclical, differentiated forms of participation.