The transformations with which the system of international relations has been confronted since the end of the 1990s are reflected in several manifestations that are familiar to us today: the decentralization of the world order following the end of the Cold War, the rise of regionalism, the emergence of new economic powers, the precariousness of international security, democratic transitions, climatic and technological changes, etc. The material and political management of the COVID-19 pandemic, since 2020, has added its share of pressure on international power relations, while putting their dogmas and operating logics to a severe test. Today, these changes also call into question the foreign policy and its international insertion system. The environment, the actors and the processes of foreign policy, as well as the observer’s view of the phenomenon, are particularly affected by these changes. At the same time, the numerous upheavals in domestic politics contribute to the evolution of the world order, diplomacy and a reconsideration of the scientific paradigms that attempt to explain these phenomena. All of these redefinitions are likely to blur the sometimes recognized, but often practised, boundary between the many sub-disciplines of political science and related analytical fields.