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Max Planck Encyclopedia of Public International Law [MPEPIL]

Inter-American Treaty of Reciprocal Assistance of Rio de Janeiro (1947)

Jean-Michel Arrighi

Regional organizations — Aggression — Armed attack — Use of force, prohibition — Use of force, threat — Specific treaties

Published under the auspices of the Max Planck Foundation for International Peace and the Rule of Law under the direction of Rüdiger Wolfrum.

A.  Historical Background

Since its origins, dating back to the end of the 19th century, the inter-American system has gradually consolidated a set of ground rules. In particular, resolutions and agreements established the principle of solidarity among American States vis-à-vis external threats and threats to peace in the region (Peace, Threat to); the obligation to seek peaceful settlement of international disputes, culminating in the adoption of the American Treaty on Pacific Settlement (Bogotá Pact [1948]) and its prohibition of the use of force (Use of Force, Prohibition of); the legal equality of States (States, Sovereign Equality); the need for collective security and regional co-operation; and the principle of non-intervention (Intervention, Prohibition of; see also Regional Co-operation and Organization: American States). At the same time, consultation and decision-making mechanisms were established among the States to facilitate the achievement of those objectives: the Conferences of American States, the Meetings of Ministers of Foreign Affairs of the American Republics, and, finally, in 1948, the Organization of American States (OAS), which would incorporate those principles and organs, as a regional agency of the United Nations (UN) for dealing with matters relating to the maintenance of international peace and security (Chapter VIII of the United Nations Charter). In the long process leading to the adoption, in 1947, of the Inter-American Treaty of Reciprocal Assistance (‘Rio Treaty’), milestones worth mentioning include the Sixth International Conference of American States of 1928, which declared that ‘war of aggression constitutes an international crime against the human species’ (Aggression), that ‘all aggression is considered illicit and as such is declared prohibited’, and that, therefore, ‘the American States will employ all pacific means to settle conflicts which may arise between them’ (Scott 441–2). In 1936 the Convention for the Maintenance, Preservation and Reestablishment of Peace established the first consultation and co-operation mechanisms ‘in the event of war, or a virtual state of war between American States … [or] in the event of an international war outside America which might menace the peace of the American Republics’ (Art. 2 Convention for the Maintenance, Preservation and Reestablishment of Peace). In 1940, after World War II had begun, the Second Meeting of Ministers of Foreign Affairs of the American Republics declared ‘that any attempt on the part of a non-American State against the integrity … of an American State shall be considered as an act of aggression against the states which sign this declaration’ (Chapter XV Second Meeting of Ministers of Foreign Affairs of the American Republics Final Act and Convention ; see also Territorial Integrity and Political Independence). Faced with the prospect of a universal charter, the American States strove to preserve the role of regional bodies in this process and, in 1945, met at the Inter-American Conference on Problems of War and Peace, at which they adopted the Act of Chapultepec, which, inter alia, urges governments to consider entering into a treaty establishing measures for dealing with threats or acts of aggression and to ‘constitute a regional arrangement for dealing with such matters relating to the maintenance of international peace and security as are appropriate for regional action in this Hemisphere’ (Part III Act of Chapultepec). Pursuant to these inter-American provisions, and to bring them into line with those of the recently adopted UN Charter—especially Art. 33 UN Charter concerning the resort to regional agencies or arrangements for the pacific settlement of disputes, Art. 51 UN Charter concerning respect to the right of collective self-defence, and Chapter VIII UN Charter concerning regional arrangements—the American States gathered in Rio de Janeiro, in 1947, for the Inter-American Conference for the Maintenance of Continental Peace and Security and adopted the Rio Treaty (Regional Arrangements and the United Nations Charter; Self-Defence, Collective).

B.  The Rio Treaty

After reaffirming the obligation not to resort to the threat or the use of force (Art. 1 Rio Treaty ; Use of Force, Prohibition of Threat) and the commitment of the High contracting parties to employ methods of peaceful settlement of any controversy that may arise among themselves (Art. 2 Rio Treaty), the Rio Treaty sets forth the cases in which the principle of solidarity should function for the collective security of the region.

The first situation is when there is an armed attack by any State against an American State (Art. 3 (1) Rio Treaty), which takes place within the region described in Art. 4 Rio Treaty, ie the entire hemisphere from the Arctic to the Antarctic (Arctic Region; Antarctica), with an adjacent sea of approximately 480km. This attack shall be considered as an attack against all the American States, warranting the exercise of the inherent right of individual or collective self-defence recognized by Art. 51 UN Charter, and, at the request of the State attacked, it prompts a meeting of the ‘Organ of Consultation’. There are two possibilities: that the armed attack against an American State is perpetrated by an extra-continental State, in which case collective self-defence is legitimate and the Organ of Consultation shall agree upon the measures of a collective character that should be taken (Art. 3 (2) Rio Treaty); or that the conflict is between two or more American States, in which case the Organ of Consultation shall agree upon measures necessary for a solution of the conflict by peaceful means (Art. 7 Rio Treaty), or, if the aggressor is identified, the Organ of Consultation may adopt one or more of the measures contemplated inArt. 8 Rio Treaty, which range from the recall of heads of diplomatic missions to the use of armed force, albeit, naturally, in conformity with the provisions of Arts 5 and 9 UN Charter (Diplomatic Relations, Establishment and Severance; Armed Forces).

The second situation is when the armed attack takes place against an American State, but outside the region described in Art. 4 Rio Treaty (Art. 3 (3) Rio Treaty). This situation may not necessarily give rise to the collective solidarity that must apply if the attack takes place within the region, so that, if requested, the Organ of Consultation may agree upon measures to assist the victim or others needed for the maintenance of peace and security of the continent.

The third situation is when the inviolability or the integrity of the territory of an American State is affected by an aggression which is not an armed attack or by an extra-continental or intra-continental conflict, or by any other fact or situation that might endanger the peace of America (Art. 6 Rio Treaty). Here, as in the previous case, the Organ of Consultation may agree on measures to assist the victim of the aggression or that are needed for the maintenance of the peace and security of the continent. This is the case most frequently invoked when the Rio Treaty has been applied.

The Organ of Consultation referred to in the Rio Treaty is the ‘Meetings of Ministers of Foreign Affairs of the American Republics’ (Art. 11 Rio Treaty). That organ, which pre-dates the Rio Treaty itself, was subsequently institutionalized in the Charter of the Organization of American States. Since the Rio Treaty was adopted prior to the constitution of the OAS, the references in it to the Governing Board of the Pan American Union, which no longer exists, should be construed to have been replaced by references to the Permanent Council of the OAS, which may act provisionally as an Organ of Consultation (Art. 12 Rio Treaty). In all instances, only the States Parties to the Rio Treaty may vote (International Organizations or Institutions, Voting Rules and Procedures). This is important because there are fewer signatories of the Rio Treaty than OAS Member States (International Organizations or Institutions, Membership), and decisions are taken on a vote of two-third of the signatory States that have ratified the Rio Treaty (Art. 17 Rio Treaty). In the case of a situation between American States, the Parties directly interested are excluded from the voting (Art. 18 Rio Treaty). Finally, Art. 20 Rio Treaty establishes that:

Decisions which require the application of the measures specified in Article 8 shall be binding upon all the Signatory States which have ratified this Treaty, with the sole exception that no State shall be required to use armed force without its consent.’

The following States are currently parties to the Rio Treaty: Argentina, Bahamas, Brazil, Chile, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, El Salvador, Guatemala, Haiti, Honduras, Panama, Paraguay, Peru, Trinidad and Tobago, United States of America, Uruguay, and Venezuela.

Since it entered into force (Treaties, Conclusion and Entry into Force), the Rio Treaty has been denounced on four occasions: by Peru, in 1990, by Mexico in 2001 and by Nicaragua and Bolivia in 2012. The Peruvian denunciation was withdrawn one year after it was filed. The Mexican denunciation meant that, as of 2004, the Rio Treaty ceased to be in force for that country in respect of all its effects (Treaties, Termination), as established in Art. 25 Rio Treaty, which states that the Rio Treaty shall cease to be in force in its effects for the denouncing High Contracting Party after expiration of two years from the date of the receipt by the current General Secretariat of the OAS (International Organizations or Institutions, Secretariats), which replaced the Secretariat of the Pan American Union, of a notification of denunciation by the High Contracting Party. For Nicaragua and Bolivia the Treaty will cease to be in force in 2014.

C.  The Protocol of Amendment

Criticism of the implementation of the Rio Treaty—which was viewed by many as an instrument of confrontation, if not intervention, in the internal affairs of Member States, rather than as an instrument for resolving conflicts in the face of real international threats—led several States to call for amendments that would update the notion of aggression, curtail the scope of the Rio Treaty’s application, and broaden the concept of security. To that end, the Conference of Plenipotentiaries was held in San José, Costa Rica, in 1975, and resulted in the Protocol of Amendment of the Inter-American Treaty of Reciprocal Assistance (‘Protocol of 1975’), which has not yet entered into force. The Protocol of 1975 incorporates the entire text of the Rio Treaty, reproducing the parts that remain unchanged and including the proposed additions, in order to facilitate a reading of the whole document (Treaties, Amendment and Revision). However, it was also accompanied by a considerable number of declaration[s] and reservations (Treaties, Multilateral, Reservations to). The Protocol of 1975 establishes that it will enter into force when two-thirds of the signatory States thereof have deposited their instruments of ratification. So far, it has been signed by 21 States, but ratified by only eight (Brazil, Costa Rica, Dominican Republic, Guatemala, Haiti, Mexico, Peru, and the US), with many of them entering reservations regarding its more novel provisions. The last instrument of ratification was deposited in 1992.

10  Among other amendments to the Rio Treaty, the Protocol of 1975 listed the acts that qualify as an act of aggression, based on the definition adopted one year earlier by UN General Assembly Resolution 3314 (XXIX) of 14 December 1974 (United Nations, General Assembly). The Protocol also narrowed the region to which the Rio Treaty applies, leaving out Greenland (see also Treaties, Territorial Application). While the Rio Treaty is applicable to an armed attack ‘against an American State [which] shall be considered as an attack against all the American States’ (Art. 3 Rio Treaty), the Protocol of 1975 only includes States Parties. The proposed new Art. 3 Protocol of 1975 establishes that ‘an armed attack by any State against a State Party shall be considered an attack against all the States Parties’. Finally, the Protocol of 1975 incorporates the concept of ‘collective economic security’, which prompted some of the ratifying States to enter a reservation. The new Art. 11 Protocol of 1975 establishes that

for the maintenance of peace and security in the Hemisphere, collective economic security for the development of the Member States of the Organization of American States must also be guaranteed through suitable mechanisms to be established in a special treaty.

D.  Application of the Treaty

11  Since its entry into force in 1948, the Rio Treaty has been invoked on 20 occasions. The first 18 cases involved situations that had arisen among American States; the last two involved an extra-hemispheric factor and occurred within the region.

12  On occasion one in 1948, the government of Costa Rica complained that armed forces originating in Nicaragua had invaded its country. Acting provisionally as the Organ of Consultation, the Permanent Council of the OAS appointed an investigation commission, which reported that the revolutionary movement operating in Costa Rica had been organized in Nicaragua. The affair ended in 1949 with the signature by both countries of the Pact of Amity between the Governments of the Republics of Costa Rica and Nicaragua ([signed 21 February 1949, entered into force 15 July 1949] 1465 UNTS 217), in which the two governments firmly resolved to prevent a repetition of these events in future and to show full respect for the principle of non-intervention.

13  On occasion two in 1950, the government of Haiti requested that the Organ of Consultation be convened on account of acts of intervention on its soil by the Dominican Republic, which, in turn, accused Haiti of threatening its security. An investigating committee was installed and, in the end, it was resolved that both States be asked to take appropriate measures to ensure respect for the principle of non-intervention.

14  On occasion three in 1954, 10 States requested convocation of the Organ of Consultation owing to the perceived threat to peace and security as a result of increasing communist intervention in Guatemala. The Organ of Consultation was convened, but then indefinitely postponed due to the change of government in Guatemala.

15  On occasion four in 1955, Costa Rica again requested application of the Rio Treaty for acts of intervention originating in Nicaragua. Both States were called upon to abide by the Pact of Amity between the governments of the Republics of Costa Rica and Nicaragua of 1949. In 1956, the new ‘Agreement between the Government of the Republics of Costa Rica and Nicaragua pursuant to Article IV of the Pact of Amity signed on 21 February 1949’ was signed.

16  On occasion five in 1942, Ecuador and Peru had signed, in Rio de Janeiro, a Protocol of Peace, Friendship, and Boundaries (Boundaries), in the presence of representatives of the guarantor countries, namely, the US, Argentina, Brazil, and Chile. Nevertheless, in 1955, Ecuador requested convocation of the Organ of Consultation, accusing Peru of amassing troops on the border. Swift intermediation by the four guarantor States rendered it unnecessary for a meeting to take place under the Rio Treaty.

17  On occasion six in 1957, the government of Honduras requested convocation of the Organ of Consultation on account of violations of its territory by Nicaragua. The investigating committee requested withdrawal of troops and negotiation of an agreement to accept the procedures for pacific settlement of controversies established in the American Treaty on Pacific Settlement (Bogotá Pact).

18  On occasion seven in 1959, the government of Panama requested convocation of the Organ of Consultation to address its complaint that a group originating in Cuba was helping national movements aiming to overthrow the government. The facts were confirmed but the group surrendered, so that the matter was considered closed.

19  On occasion eight also in 1959, Nicaragua denounced Costa Rica for supporting an armed invasion. The investigating committee appointed by the Organ of Consultation concluded that the situation had been resolved.

20  On occasion nine in 1960, Venezuela lodged a complaint against the Dominican Republic for intervention and aggression, including an attempted assassination of the Head of State. The meeting of the Organ of Consultation condemned the Dominican Republic and resolved that all Member States would sever diplomatic ties with it. This sanction was lifted in 1962 (Sanctions).

21  On occasion 10 in 1961, at Colombia’s request, Cuba was accused of illegal acts against that country’s government and of ‘communist infiltration’. The meeting of the Organ of Consultation, held in January 1962, resolved to exclude the government of Cuba from participation in the organs of the inter-American system.

22  On occasion 11 in 1962, Bolivia requested convocation of the Organ of Consultation, accusing Chile of wanting to divert the waters of the Lauca River, thereby impairing its territorial integrity (International Watercourses; Water, International Regulation of the Use of). The Council called upon the two governments to resort to pacific means for settling the dispute.

23  On occasion 12 also in 1962, during the so-called Cuban Missile Crisis, the US government accused the government of Cuba of allowing the installation of Soviet missiles on its territory. Acting provisionally as the Organ of Consultation, the Council recommended that Member States adopt measures to prevent the provision of military equipment to Cuba, a policy known as ‘quarantine’ (see also Military Assistance). This issue ended in November 1962 with the withdrawal of offensive military material from Cuban territory. As it implied the possible use of force, the issue prompted hefty political and legal debate of the relationship between the regional and the universal system, of the relationship between a regional organization and the UN, and of the competencies of the Organ of Consultation and those of the UN Security Council (United Nations, Security Council; International Organizations or Institutions, External Relations and co-operation).

24  On occasion 13 in April 1963, the government of the Dominican Republic complained that Haitian police had raided its embassy in Haiti, where there were Haitian political refugees. An investigating committee was appointed and the OAS Permanent Council, as the acting Organ of Consultation, asked the government of Haiti to grant the refugees safe conduct. Once this was settled, the matter was considered closed.

25  On occasion 14 in December 1963, the government of Venezuela complained of acts of intervention and aggression on its territory fostered by the government of Cuba. The meeting of the Organ of Consultation asked Member States to sever diplomatic, consular, and trade relations with Cuba. Several States entered reservations with respect to this decision and some did not comply with it (Trading with the Enemy).

26  On occasion 15 in 1964, Panama denounced the US government for having allowed its troops, stationed in the Panama Canal Zone, to enter Panamanian territory. Under the terms of the Rio Treaty, the OAS Permanent Council established an investigating committee. Finally, the two governments issued a joint declaration in 1965, in which they undertook to conclude a new treaty on the rules governing the Panama Canal, which would recognize Panama’s sovereignty over this zone, a commitment that eventually materialized in 1977, with the Panama Canal Treaty of 7 September 1977 ([1977] 16 ILM 1022).

27  On occasion 16 in 1969, there was a series of clashes between the armed forces of Honduras and El Salvador. The meeting of the Organ of Consultation embarked on a long process aimed at settling the border conflicts by pacific means, which culminated, in 1980, in the adoption of the General Peace Treaty between the Republics of El Salvador and Honduras ([signed 30 October 1980, entered into force 10 December 1980] 1310 UNTS 226 ; see also Peace Treaties).

28  On occasion 17 in 1975, the meeting of the Organ of Consultation left Member States free to normalize their bilateral relations with Cuba, if they so wished.

29  On occasion 18 in 1978, Costa Rica once again complained of threats originating in Nicaragua. Acting provisionally as the Organ of Consultation, the OAS Permanent Council reaffirmed the principle of prohibition of the threat or the use of force and urged the governments to comply with the principles set forth in the OAS Charter.

30  On occasion 19 in 1982, Argentine troops disembarked in the Falkland Islands/Islas Malvinas over which Argentina claims sovereignty. Invoking its right to legitimate self-defence, the United Kingdom dispatched a strong contingent of troops. The matter was considered by both the UN Security Council and the meeting of the Organ of Consultation in the framework of the Rio Treaty. In the latter, there were three interpretations of the legal provisions in force with respect to competence (Interpretation in International Law): some were of the opinion that the matter belonged exclusively in the purview of the UN, another group considered that the OAS was the competent body, and a third group favoured joint action by both organizations. This, in turn, reflected three positions in respect of the facts: those who opposed Argentina’s action, those who sympathized with it out of solidarity, and those who sought to reconcile the other two approaches. These splits prevented the Organ of Consultation from making a pronouncement. Meanwhile, after fierce battles, the British troops won surrender from Argentina.

31  On occasion 20, when the Rio Treaty was already frequently being referred to as a ‘dead letter’, having fallen into discredit following the conflict in the Southern Atlantic and because no State invoked it during the serious conflicts in Central America in the 1980s, the terrorist attacks on North American soil on 11 September 2001 prompted convocation of the Organ of Consultation, at Brazil’s request (Terrorism). That Organ of Consultation reaffirmed hemispheric solidarity and reciprocal assistance in dealing with attacks of that nature.

E.  Evaluation

32  The Treaty now has 20 States parties, out of the 35 Member States that today make up the OAS. They include almost all the Latin American countries, the United States of America, and only some of the English-speaking Caribbean countries. The Protocol of Amendment, signed in 1975, has not entered into force, for lack of the requisite number of ratifications, and it is unlikely to do so, at least in the near future.

33  Originally conceived as an instrument primarily designed to protect the region from extra-hemispheric attacks, the Rio Treaty has been invoked 20 times. On 18 of those occasions, it was invoked in conflicts between American States, most of them in Central America or the Caribbean, in circumstances alleged to be covered, above all, by Art. 6 Rio Treaty. The Rio Treaty was invoked once in the 1940s, seven times in the 1950s, eight times in the 1960s, and twice in the 1970s. Most of those matters were also brought to the attention of the UN, which, for various reasons, did not act, leaving it up to the Organ of Consultation to find solutions. The two situations involving extra-regional factors occurred, in one case, in the 1980s, and, in the other, at the start of the 21st century. In other words, what should have been the exception, ie intra-regional conflicts, was the rule; and when nobody imagined it would be used again, the circumstances surrounding the terrorist attacks of 11 September 2001 prompted its application. It is therefore difficult to predict whether, and in what circumstances, the Rio Treaty might again be invoked in the future.

34  An effort has been made in the OAS framework in recent years to develop the concept of ‘multidimensional security’, which covers, in addition to the factors already contemplated in the Rio Treaty, numerous new threats it did not envisage, such as organized crime, drug trafficking, and terrorism. Such threats also require joint action, co-operation, and hemispheric solidarity, which in some cases are already covered by specific inter-American conventions.