The study deals with the problem of mediation in the settlement of the longest territorial conflict in Latin America between Peru and Ecuador, highlighting its origins. The main goal of conflict resolution is not only the elimination of the conflict itself, but the transformation of a real conflict situation into a peaceful process of social or political change, where mediation is a strategy or a tool to end the conflict. The authors use an integrated approach, where the most appropriate theoretical basis for considering and resolving these conflicts is neoliberalism, as well as the problem-chronological approach, the historical method, which makes it possible to trace the prerequisites and the development of the territorial conflict, and mediation efforts to resolve it. It was concluded that the Ecuadorian-Peruvian war, although it was the result of the perception of divergent territorial interests, was caused by the unsuccessful mediation activities of the guarantor countries (Brazil, USA, Chile and Argentina). The mediation activities of Brazil, the USA, Chile and Argentina in 1995-1998 led to the so-called “elegant agreement,” one way or another taking into account the interests of Peru and Ecuador. In this regard, the special importance of the mediation activities of the guarantor countries in resolving the conflict was emphasized, as well as their main tools, such as: negotiation processes, signing documents on the territorial dispute, participating in the demarcation of borders, monitoring compliance with the agreements reached, contributing to the active development of Ecuadorian-Peruvian relations after the signing of the peace treaty and preventing the escalation of the conflict in the future. As a result of the consideration of the role of each intermediary country in the settlement of the Alto Cenepa conflict, their own interests were touched and the key areas of participation in peacekeeping activities were listed, and it was concluded that Brazil’s position was the most active.