Studies on international relations increasingly focus on actors at the sub-state level. The terms para-diplomacy or proto-diplomacy are used to describe international activities of state institutions below the national level and outside the foreign services. In this special issue, we have collected seven case studies from Europe, North America and Asia, where the authors analyse recent developments of de- and re-bordering focusing on the role of non-central state actors with regard to cooperation, reconciliation and peace-building. The cases demonstrate the wide range of multi-level governance and personal interaction of cross-border regions, but also the persistence of the central state as a norm-setting actor of international relations. We suggest labelling these activities of local international relations secondary foreign policy, widening and précising the terms of para-diplomacy or proto-diplomacy used within Political Sciences to describe regional, non-central state activities in international relations.