Inter-American Treaty of Reciprocal Assistance

Rio Treaty
Inter-American Treaty of Reciprocal Assistance
Traité interaméricain d'assistance réciproque
Tratado Interamericano de Assistência Recíproca
Tratado Interamericano de Asistencia Recíproca
Member states in green with Venezuela in light green.[a]
Signed2 September 1947[1]
LocationRio de Janeiro[1]
Effective3 December 1948[1]
ConditionRatification by two-thirds of the signatory states
Signatories23[1]
Parties18[1]
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 intergovernmental collective security agreement signed in 1947 in Rio de Janeiro among many countries of the Americas.[2][3]

The central principle contained in its articles is that an attack against one is to be considered an attack against them all;[3] this was known as the "hemispheric defense" doctrine.[4] 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]


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  1. ^ a b c d e f "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 Kunz, Josef L. (1948). "The Inter-American Treaty of Reciprocal Assistance". The American Journal of International Law. 42 (1): 111–120. doi:10.2307/2193568. ISSN 0002-9300. JSTOR 2193568.
  4. ^ Wragg, David W. (1973). A Dictionary of Aviation (first ed.). Osprey. p. 163. ISBN 9780850451634.