The Good Neighbor Policy, launched by President Franklin D. Roosevelt in 1933, was a pivotal shift in US foreign policy toward Latin America. While primarily aimed at repairing relations damaged by decades of military intervention and "gunboat diplomacy," it was explicitly motivated by the rise of aggressive fascist governments in Europe (Nazi Germany, Fascist Italy).
Roosevelt feared that European fascist powers would exploit anti-American sentiment in Latin America to gain strategic footholds. By embracing cooperation and respect for sovereignty, the US sought to solidify the hemisphere as a united democratic bloc.
The policy successfully improved hemispheric relations. Most Latin American nations joined the Allies in WWII, providing vital raw materials and bases. It laid groundwork for the 1947 Rio Treaty and the OAS.