The Peru-Ecuador boundary issue is the oldest continuing border
dispute in the Western Hemisphere. Furthermore,
[it] has caused more trouble than any other in America .... baffl[ing] repeated attempts at settlement by direct negotiation and repeated efforts at mediation on the part of other friendly nations.... (McBride, 1949: 1).
In 1942, four such friendly nations brought Peru and Ecuador together, after a short but bitter war between them, to settle their differences once and for all by signing a treaty of “Peace, Friendship, and Boundaries,” known as the Rio Protocol. These four countries were Argentina, Brazil, Chile, and the United States. Their representatives also signed that treaty, “as guarantors that the Protocol would be faithfully executed....” (McBride, 1949: 2-3).