Inter-American Treaty of Reciprocal Assistance

The Inter-American Treaty of Reciprocal Assistance (commonly known as the Rio Treaty, the Rio Pact, the Treaty of Reciprocal Assistance, or by the Spanish-language acronym TIAR from Tratado Interamericano de Asistencia Recíproca) is an intergovernmental collective security agreement signed in 1947 in Rio de Janeiro, Brazil at a meeting of the American states.

The central principle contained in its articles is that an attack against one is to be considered an attack against them all; this was known as the "hemispheric defense" doctrine. Despite this, several members have breached the treaty on multiple occasions.

The treaty was initially created in 1947 and came into force in 1948, in accordance with Article 22 of the treaty. The Bahamas was the most recent country to sign and ratify it in 1982.

The United States maintained a hemispheric defense policy relative to European influence under the Monroe Doctrine from 1823 onward, and became increasingly interventionist following the 1904 promulgation of the Roosevelt Corollary. During the 1930s the United States had been alarmed by Axis overtures suggesting military cooperation with Latin American governments; apparent strategic threats against the Panama Canal were of particular concern. These were discussed in a series of meetings of the International Conference of American States and at the 1936 Inter-American Conference for the Maintenance of Peace. During World War II, the American government had been able to secure support for the Allies from all individual governments in the Americas except Uruguay (which remained neutral until 22 February 1945) and Argentina (which had difficult relations with the Allied powers from 1944 to 1945 but declared war on the Axis on 27 March 1945). Some countries had signed the Declaration by United Nations in early 1942 and more had signed by the end of 1945.

However, Latin American countries were largely sidelined from the Allied discussions of a postwar security order, held at Dumbarton Oaks from August to October 1944. The Brazilian Ambassador to Washington, Carlos Martins Pereira e Souza, "protested the violation of inter-American norms of consultation in the preparation of postwar plans." These protests led to a series of consultations as well as to a Mexican proposal for an inter-American meeting. At the Inter-American Conference on the Problems of War and Peace, at Chapultepec Castle in Mexico City during February and March 1945, discussions of the post-war world order were held by the US Secretary of State and by the foreign secretaries of all the Latin American countries except El Salvador and Argentina, resulting in the Act of Chapultepec of 6 March 1945. The Act included a framework for the negotiation of a regional security treaty. It also shaped Latin American pressure during the United Nations conference in San Francisco for clauses in the UN Charter to facilitate regional collective defense, under Article 51.

Initially, the security conference was planned to be held in Rio de Janeiro in October 1945 but it was postponed to March 1946. The March 1946 date was also postponed indefinitely. Disputes between the United States and Argentina's Juan Perón (President from 4 June 1946) led to the delays. The American concern, alongside that of some countries in South America regarding Peronism raised the possibility of including collective intervention to preserve democracy in the security conference. During the delay, global tensions between the United States and Soviet Union grew. In light of the developing Cold War and following the statement of the Truman Doctrine on 12 March 1947, the United States wished to make those^[which?] new anti-communist commitments permanent, as did many anti-communist leaders in Latin America.^{[citation needed]}

The following year, in 1948, delegates gathered in Bogotá, Colombia, where they passed the charter of the Organization of American States (OAS). The OAS was created to oversee different functions beyond defense. The OAS functioned through debate and voting instead of the like-mindedness that characterized NATO.

The Inter-American Treaty of Reciprocal Assistance was the first of many so-called "mutual security agreements", and the formalization of the Act of Chapultepec. The treaty was adopted by the original signatories on 2 September 1947 in Rio de Janeiro (hence the colloquial name "Rio Treaty"). It came into force on 3 December 1948 and was registered with the United Nations on 20 December 1948. With the exceptions of Trinidad and Tobago (1967) and the Bahamas (1982), no countries that became independent after 1947 have joined the treaty; Canada is yet to become a member, though it already has separate defense commitments with the United States.