Rio Pact

Mutual defense agreement signed in 1947 by the United States and 19 Latin American countries. Under the terms of the Rio Pact, an attack against any of the signatory nations is regarded as an attack against all. The pact provides for all signatories to send troops in defense of any member that is the target of foreign aggression.

The Rio Pact was both an extension of the Monroe Doctrine of the 19th century and a product of the 20th century Cold War. The Monroe Doctrine, outlined by U.S. President James Monroe in 1823, declared the western hemisphere off-limits to European intervention. It stated that the United States would regard any attempt by foreign powers to interfere in Latin America to be an act of aggression against the United States. The Monroe Doctrine, however, was a unilateral declaration by the United States. It reflected a desire to create an exclusive U.S. sphere of influence in the western hemisphere rather than a collective statement of solidarity among western nations.

Fears about the spread of Soviet communism after World War II led the United States to seek a more [Page 631]active alliance with other Western-Hemisphere nations. Thus, on September 2, 1947, the United States and 19 Latin American countries signed the Rio Pact, which created a hemisphere-wide security zone. Under the pact, members agreed to refrain from aggression against each other, as well as to defend one another from outside aggression. The Rio Pact authorizes the use of force to resist aggression if two-thirds of the members vote to do so. Each member nation, however, must consent to the use of its troops in any military action. The Rio Pact was the first formal regional defense agreement concluded under the terms of Article 51 of the United Nations Charter. It also served as a model for the North Atlantic Treaty that created the North Atlantic Treaty Organization (NATO) in 1949.

As the perceived Soviet threat to the Western Hemisphere decreased, the Rio Pact became less important for U.S. foreign policy. For example, Argentina invoked the pact in 1982 to obtain U.S. assistance in the Falklands War against Great Britain, but the United States backed the British in that conflict. However, after the September 11, 2001, terrorist attacks against New York City and Washington, DC, some Western-Hemisphere nations—particularly Brazil—have talked of reviving the Rio Pact in response to the threat of international terrorism. These suggestions have been met with a positive response from the administration of U.S. President George W. Bush.