Rio Pact
Inter-American Treaty of Reciprocal Assistance
Traité interaméricain d'assistance réciproque
Tratado Interamericano de Assistência Recíproca
Tratado Interamericano de Asistencia Recíproca
Rio Pact (orthographic projection).svg
Member states in green with Venezuela in light green.[a]
Signed2 September 1947[1]
LocationRio de Janeiro[1]
Effective3 December 1948[1]
ConditionRatifications of two-thirds of the Signatory States
DepositaryPan American Union
LanguagesEnglish, French, Portuguese and Spanish

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 agreement signed in 1947 in Rio de Janeiro among many countries of the Americas.[2] 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.[1]


The United States maintained a hemispheric defense policy relative to European influence under the Monroe Doctrine since 1823, which became increasingly interventionist with the Roosevelt Corollary in 1904. During the 1930s the United States had been alarmed by Axis overtures toward 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 the 1936 Inter-American Conference for the Maintenance of Peace.[3] During the war, Washington had been able to secure Allied support from all individual governments except Uruguay, which remained neutral, and Argentina, whose government was not recognized by the Allied powers.[3] 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. The Brazilian Ambassador Carlos Martins "protested the violation of inter-American norms of consultation in the preparation of postwar plans."[4] These protests led to a series of consultations as well as the Mexican proposal for an inter-American meeting. At the Inter-American Conference on the Problems of War and Peace, in Mexico City during February and March 1945, discussions of the post-war world order were held and produced the Act of Chapultepec.[3][5] 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.[4][6]

Initially, the security conference was due to be held in Rio de Janeiro in late 1945 or early 1946; however, disputes between the United States and Argentina's Juan Domingo Perón led to delays. The United States and some Latin American concern about peronismo raised the possibility of including collective intervention to preserve democracy in the security conference.[7] 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, the United States wished to make those new anti-communist commitments permanent, as did many anti-communist leaders in Latin America.



The Inter-American Treaty of Reciprocal Assistance was the first of many so-called "mutual security agreements",[8] 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.[1] 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.

Cold War

Though the Cold War overtones of the Rio Treaty became increasingly evident, during the immediate post-war years, Long argues that it was more closely tied to pre-WWII regional antecedents and, even, Latin American diplomatic pressure. Long states, "Despite many Latin American concerns about the United States’ ultimately interventionist nature, Latin American diplomats cited the Monroe Doctrine and United States-led Pan-Americanism in support of a grand bargain that would extend and institutionalize U.S. engagement while restricting unilateralism."[4] However, the United States' often considered adherence to the Treaty's principles of nonintervention as secondary to its Cold War concerns.


As revolutionary and nationalist governments spread through Latin America through the 1950s and 1960s, the fear of a shared enemy that was experienced during WWII dissipated and the idea of defensive cooperation became strained.[9] According to Slater, many Latin American governments participating in the Treaty sought "to insulate the hemisphere from rather than involve it in world conflict", though the United States pushed the smaller countries towards confrontation with its ideological adversaries.[9] Latin American governments then began to view inter-American collaboration as bending to the will of the United States, forfeiting their sovereignty.[9]

Though the action of the United States during the 1954 Guatemalan coup d'état and the 1961 Bay of Pigs Invasion raised questions among Latin American governments, the unilateral approach of the United States invading the Dominican Republic in 1965 during the Dominican Civil War before the OAS's Inter-American Peace Force was organized, proved to members that the United States did not respect the ideals of multilateralism.[9] Conversely during the Falklands War in 1982, the United States favored the United Kingdom arguing that Argentina had been the aggressor and because Argentina had not been attacked, as did Chile and Colombia. This was seen by most Latin American countries as the final failure of the treaty.[10][11]

In September 2002, citing the Falklands example[12][13] and anticipating the invasion of Iraq, Mexico formally withdrew from the treaty; after the requisite two years, Mexico ceased to be a signatory in September 2004. In 2008, the Union of South American Nations (UNASUR) created a new regional security council manage their own defensive objectives.[14][15] On 5 June 2012, Bolivarian Alliance for the Americas (ALBA) countries Bolivia, Ecuador, Nicaragua, and Venezuela, under the leadership of leftist governments, initiated the retirement from the TIAR,[16][17] a decision which the Obama administration described as "unfortunate" but respected.[18] The treaty was officially denounced by Nicaragua on 20 September 2012, Bolivia on 17 October 2012, Venezuela on 14 May 2013, and Ecuador on 19 February 2014.

Invocations and considerations

The treaty was invoked numerous times during the 1950s and 1960s, in particular the unanimous support of the United States' naval blockade during the Cuban Missile Crisis. In 2001, the United States invoked the Rio Treaty after the September 11 attacks.

In 2019 during a presidential crisis in Venezuela between incumbent President Nicolás Maduro and president of the opposition-led National Assembly of Venezuela Juan Guaidó, the latter opened talks on rejoining TIAR.[19] On 11 May, Guaidó sent a letter to Organization of American States (OAS) secretary Luis Almagro requesting that Venezuela be reinstated.[20] On 29 May 2019, the National Assembly approved its return to the Treaty in a preliminary discussion.[21] The National Assembly reiterated its approval to return to the treaty in July 2019.[22]


Current members:[23]

Suspended members:

Former members:

See also


  1. ^ a b Venezuela denounced the treaty in 2013. However, the denunciation was disputed during the Venezuelan presidential crisis. As of July 2019, reincorporation was approved by the National Assembly and ratified by the OAS.[22]
  2. ^ Uruguay denounced the treaty in 2019. However, the denunciation was withdrawn in 2020.[24]
  3. ^ Cuba was suspended from the rights and obligations of the treaty in 1962.[25]
  4. ^ Bolivia denounced the treaty in 2012.
  5. ^ Ecuador denounced the treaty in 2014.
  6. ^ Mexico denounced the treaty in 2002.
  7. ^ Nicaragua denounced the treaty in 2012.

Further reading


  1. ^ a b c d e f g "B-29: INTER-AMERICAN TREATY OF RECIPROCAL ASSISTANCE (RIO TREATY)". Organization of American States. Retrieved 1 March 2014.
  2. ^ n.d. (2013). "Inter-American Treaty of Reciprocal Assistance.". The Columbia Electronic Encyclopedia®. Columbia University Press. Retrieved August 31, 2018.
  3. ^ a b c Act of Chapultepec The Oxford Companion to World War II, 2001, I. C. B. Dear and M. R. D. Foot
  4. ^ a b c Long, Tom (April 2020). "Historical Antecedents and Post-World War II Regionalism in the Americas". World Politics. 72 (2): 214–253. doi:10.1017/S0043887119000194. ISSN 0043-8871. S2CID 213565127.
  5. ^ Act of Chapultepec: Declarations on Reciprocal Assistance and American Solidarity, March 3, 1945, Pillars of Peace, Documents Pertaining To American Interest In Establishing A Lasting World Peace: January 1941-February 1946, Book Department, Army Information School, Carlisle Barracks, Pa., May 1946
  6. ^ Tillapaugh, J. (January 1978). "Closed Hemisphere and Open World? The Dispute Over Regional Security at the U.N. Conference, 1945". Diplomatic History. 2 (1): 25–42. doi:10.1111/j.1467-7709.1978.tb00420.x. ISSN 0145-2096.
  7. ^ Long, Tom; Friedman, Max Paul (n.d.). "The Promise of Precommitment in Democracy and Human Rights: The Hopeful, Forgotten Failure of the Larreta Doctrine". Perspectives on Politics. 18 (4): 1088–1103. doi:10.1017/S1537592719002676. ISSN 1537-5927.
  8. ^ "Alliances, Coalitions, and Ententes - The american alliance system: an unamerican tradition". Encyclopedia of the New American Nation. Advameg, Inc. 2018. Retrieved August 31, 2018.
  9. ^ a b c d Slater, Jerome (Summer 1969). "The Decline of the OAS". International Journal. 24 (3): 497–506.
  10. ^ Sennes, Ricardo; Onuki, Janina; de Oliveira, Amacio Jorge (2006). "The Brazilian foreign policy and the hemispheric security". Revista Fuerzas Armadas y Sociedad. Santiago. 1 (SE). doi:10.1590/S0717-14982006000100001. ISSN 0717-1498. Additionally, the deep weakening of hemispheric relations occurred due to the American support, without mediation, to the United Kingdom in the Falklands war in 1982, which definitively turned TIAR in dead letter.
  11. ^ Malamud, Carlos (30 September 2002). "México abandona el TIAR. Implicaciones continentales de la iniciativa" (PDF). Boletín Elcano (in Spanish). Real Instituto Elcano. 5: 1–5. ISSN 1696-3326. Retrieved 1 September 2018. El episodio dejó un mal sabor de boca en muchas de las cancillerías latinoamericanas, que pensaban que el TIAR era un mero papel mojado o una herramienta sólo al servicio de EEUU.
  12. ^ "OEA: México abandona el TIAR". BBC Mundo (in Spanish). Servicio Mundial de la BBC. BBC. 6 September 2002. Retrieved August 31, 2018.
  13. ^ OAS official document: He cited the 1982 conflict over the Falkland Islands as a classic demonstration of the Treaty's failure
  14. ^ "Nace UNASUR y alianza militar sin EE.UU". Archived from the original on 2011-07-24. Retrieved 2009-06-19.
  15. ^ FILATINA (April 14, 2009). "La defensa regional en manos propias: UNASUR". BLOG DE FILATINA (Fundación Integradora Latinoamericana). Fundación Integradora Latinoamericana Ambiental. Retrieved 1 September 2018.
  16. ^ Periódico La Jornada (6 June 2012). "Bolivia, Ecuador, Nicaragua y Venezuela dejan el mecanismo de defensa TIAR". La Jornada (in Mexican Spanish). No. Mundo. DEMOS S.A. de C.V. Afp, Dpa, Xinhua y Reuters. p. 31. Retrieved 1 September 2018.
  17. ^ "ALBA countries renounced the TIAR in OAS Assembly". Archived from the original on 2015-01-08. Retrieved 2013-06-01.
  18. ^ "EEUU lamenta que Bolivia, Ecuador, Nicaragua y Venezuela se retiren de TIAR". El Universal (in Spanish). 6 June 2012. Archived from the original on 20 December 2013.
  19. ^ Faiola, Anthony; DeYoung, Karen (7 May 2019). "Venezuela's Opposition Debates New Tactics". The Washington Post. Retrieved 9 May 2019.
  20. ^ "Qué es TIAR, el tratado de defensa que Guaidó ve como opción para rescatar la democracia". TalCual (in Spanish). 14 May 2019. Retrieved 19 May 2019.
  21. ^ Alvarado, Yudith (29 May 2019). "Asamblea Nacional aprobó en primera discusión adhesión al TIAR". El Universal. Retrieved 29 May 2019.
  22. ^ a b "Venezuela rejoins regional defense treaty but Guaido warns it's no 'magic' solution". Reuters. 23 July 2019. Retrieved 23 July 2019.
  23. ^ "Inter-American Treaty of Reciprocal Assistance (Rio Treaty)". Organization of American States. 8 August 2019. Retrieved 23 August 2019.
  24. ^ "Gobierno anunció el retiro de Uruguay de la Unasur y el reingreso al TIAR". El País (in Spanish). 10 March 2020. Retrieved 11 March 2020.
  25. ^ "Cuba sanctions, imposed in 1964, lifted by O.A.S." 30 July 1975. Retrieved 6 April 2022.