This dissertation investigates the role of Ambassador Lincoln Gordon s diplomatic correspondence in mediating a United States intervention in Brazil in the period leading up to the 1964 civil-military coup. With this objective in mind, the study is structured into three chapters. In the first chapter, we analyze the U.S. foreign policy towards Latin America and historically contextualize relations between Brazil and the United States in the 1940s, 1950s, and 1960s. The second chapter explores the field of Diplomatic Studies, proposing its integration with a post-structuralist Foreign Policy Analysis. This dialogue allows us to examine the role of diplomatic telegrams as instruments that construct subjects, objects, and realities, which in turn enable certain foreign policy decisions. From this perspective, Ambassador Lincoln Gordon s diplomatic telegrams mediate the construction of American narratives and perceptions of the other whether Brazilian political or military actors or Brazil itself as a nation. Finally, the third chapter empirically examines how the telegrams and dispatches sent by Lincoln Gordon to the U.S. government, reporting on the events of the two years preceding the 1964 coup, created the conditions of possibility for strategic decisions. This was achieved through the construction of representations of Brazilian political actors, particularly President João Goulart and members of the Brazilian armed forces, especially the Army.We argue that diplomacy, far from being merely a functional instrument of foreign policy, actively constructs reality-including subjects, objects, and relationships-through its textual production. This reality, in turn, shaped U.S. intervention in Brazil, contributing to the deposition of President João Goulart and the support for the civil-military conspiracy. We contend that a critical analysis of Lincoln Gordon s diplomatic correspondence not only sheds light on the discursive environment in which U.S. foreign policy toward Brazil was formulated but also reveals how an interventionist course of action became legitimate. In this sense, this dissertation contributes to understanding how diplomatic actors and instruments actively produce what is often taken as given: the state, its interests, and its identity. Diplomacy, therefore, serves as a mediator of the very elements that constitute what we call international relations.