The Central American War was a series of military conflicts between the pro-independence forces of Panama, Costa Rica, and Nicaragua (backed by the United States and Japan) and the pro-union forces of Honduras, El Salvador, and Guatemala. The war started in 1972 after the death of Director-General Manuel Mendoza. Panamanian forces immediately sought independence from the rest of the nation, which was always culturally different from Panama. The United States declared support for Panama as relations with the United Federation had slowly become hostile after the Fifth World War. By 1973, Nicaragua and Honduras had joined Panama in seeking independence, with American and now Japanese backing. Russia intervened on the side of the the Federation, seeking to maintain the presence of a major anti-American nation in the region. The war degenerated into a stalemate by the start of the next year, and Russia and the United States arranged for peace talks to start in neutral land. It was decided that the United Federation would cease claiming the three southern provinces which would become independent under Panama. The treaty was signed in 1975 and its results have remained intact to the present.