Nuclear Cooperation or Competition? Argentina and Brazil in the Evolving Landscape of Nuclear Governance 

Abstract

Despite a history of rivalry, Argentina and Brazil have turned nuclear technology into a tool for rapprochement rather than competition. Recent developments — Brazil’s nuclear-fueled submarine and Argentina’s new nuclear energy plan — are not signs of an arms race, but reflect their ambition to strengthen their international position, rooted in a Latin American security logic based on disarmament rather than deterrence.

Argentina-Brazil relations: from rivalry to rapprochment

The rivalry between Argentina and Brazil probably started with their status as former colonies of the Spanish Empire and of Portugal, respectively. Regardless, after their independence (early 19^th century), they resorted to armed conflict once only (1825-1828). However, they backed opposite sides, for instance during the World Wars, and they had disputes over resources and territories. Therefore, their development of independent and indigenous nuclear programs could have led to a nuclear competition and to direct conflict. However, it was not the case, due to the political development of the two countries, which aligned their interests in two different periods: during their military regimes and during their return to civilian rule (Institute for Science and International Security).

During military regimes in Argentina and Brazil, their interests aligned because both started to advocate for a treaty regarding the establishment of a Nuclear Weapon Free Zone (NWFZ) that would not undermine their nuclear programs. As a fact, Brazil had proposed the idea of a Latin American NWFZ in 1962, the year before the Cuban Missile Crisis occurred. Shortly after Brazil underwent a military coup, while Argentina was already under a military regime (Institute for Science and International Security).

In the ‘80s they returned to civilian government (Institute for Science and International Security) and, once again, their interests aligned – also due to the previous rapprochement. So, in the ‘90s, they ratified the 1967 Treaty of Tlatelolco (US Department of State Archive), which created the first NWFZ (IAEA). Their cooperation went further than that: they started informing each other systematically and in advance of meaningful nuclear events in their countries. Thus, nuclear development became the starting point for enhancing their rapprochement, instead of deepening their hostility (Institute for Science and International Security). 

The path of rapprochment – started in the ‘60s – led to two further milestones in the ‘90s: the creation of ABACC and the signing of the Quadripartite Agreement. ABACC is a binational agency responsible for the application of a safeguards system that applies to all nuclear activities in both countries. It is a formalization of Argentina and Brazil’s declarations on using nuclear material for peaceful purposes only (The Nuclear Threat Initiative). Concerning the Quadripartite Agreement, it establishes that the IAEA is entitled to ensure the application of safeguards (The Nuclear Threat Initiative) and represents the understanding of both countries that they had to go beyond bilateral agreements and enter into international negotiations to demonstrate their peaceful intentions (Institute for Science and International Security). Then, they both ratified the Non Proliferation Treaty (NPT) – Argentina in 1995, Brazil in 1998 (UN).

It is important to underline that both countries had developed all steps to produce fissile material, so the reason why they decided to limit themselves to peaceful purposes cannot be attributed to lack of technical expertise (Arms Control Association).

Change in the status quo: Brazil’s nuclear-fueled submarine and Argentina’s new nuclear program

In 2022, Brazil entered into negotiations with the IAEA to use nuclear fuel in its submarines. Brazil aims at deploying its nuclear-fueled submarine in the early 2030s (Arms Control Association). 

The last IAEA report (Nov. 2025) underlines cooperation through periodic meetings and the establishment of a Technical Working Group (Arms Control Association). However, concerns remain: Special Procedures negotiated according to article 13 of the Quadripartite Agreement allows to soften safeguards in the case of nuclear material used for nuclear propulsion; softening safeguards could conflict with the power of IAEA to carry out special inspections under the Treaty of Tlatelolco, and there is uncertainty on how this would be resolved (Carnegie Endowment for International Peace).

Brazil is not the only country developing a nuclear submarine. Australia is also exploring this possibility, in the framework of AUKUS. Concerns are due to the fact that, until that moment, no NPT party had nuclear submarines, except France, UK, USA, Russia and China, which are nuclear weapon state (NWS) – India also has a nuclear submarine, but it is not a party to the NPT (Reuters) –; notably, nuclear weapon states are not subject to the same nuclear governance (Carnegie Endowment for International Peace).

Concerning Argentina, in December 2024, President Milei presented a new nuclear program, highlighting the following (World Nuclear News, Oficina del Presidente on Youtube):

• New technologies, such as AI, need new forms of energy to be powered: ‘nuclear energy is the only source that is sufficiently efficient, abundant and rapidly scalable to cope with the development of our civilization’.                   
• Argentina aims at being a pioneer in the resurgence of nuclear energy and will develop this energy internally and                   autonomously.
• The nuclear program consists of two steps: firstly, the construction of a small modular reactor (SMR), developed autonomously; secondly, the development of uranium reserves, which will serve to cover domestic demand and position the country as an exporter of high value-added fuel elements (Chequeando, Oficina del Presidente on Youtube).

What are Argentina’s nuclear capabilities? There are three operable reactors (Atucha 1, Atucha 2 and Embalse), which generate 5-6% of Argentina’s electricity (World Nuclear Association). Another reactor, CAREM25, is under construction (World Nuclear Association): this is the above-mentioned small modular reactor (SMR), a research prototype that is not yet deployed anywhere in the world (Chequeando).

There are currently 17 uranium projects in Argentina (Chequeando) and all of them are still in the prospecting and initial exploration phase (Chequeando).

A last issue that needs to be addressed regards the Treaty on the Prohibition of Nuclear Weapons (TPNW), which has not been ratified by Argentina and Brazil (International Campaign to Abolish Nuclear Weapons).

Hypothesis

The recent developments concerning Brazil entering into negotiations with the IAEA and Argentina’s new nuclear program are perceived as important changes. However, regarding nuclear power, security is perceived differently when comparing Europe and Latin America. 

Therefore, the fact that Brazil formalized its request for Special Procedures regarding safeguards, or the fact that Argentina announced a new nuclear program, does not mean that the region feels threatened or that a menace for the region is emerging. Latin America applies a security logic based on disarmament, which is different from the logic of non-proliferation and deterrence to which Europe is more accustomed.

The development of nuclear technology is not perceived as a harbinger of the development of nuclear weapons. Argentina and Brazil are rather pursuing the development of nuclear energy to boost their position in the international arena, without aiming at undermining the nuclear governance-related treaties ratified to date. 

Scenarios and conclusions

A first element that explains the hypothesis relies on the concept of security upheld by Latin American states. They understand security as disarmament, not as non-proliferation (hence, deterrence). 

Non-proliferation is the logic that is mainly supported by nuclear weapon states: they argue that they hold a nuclear weapon because they need it for deterrence. 

On the other hand, disarmament served as the core concept for the establishment of Latin America as a Nuclear Weapon Free Zone (NWFZ). The idea of a NWFZ was proposed by Brazil before the Cuban Missile Crisis, but the crisis probably pushed the idea forward – having such a threat in their territory, and it being under the control of third states, was enough to advocate for disarmament, instead of mere non-proliferation. 

In addition to this, many countries, first and foremost Brazil, do not share the bipartite logic of the NPT: on the one hand, countries that developed a nuclear weapon before 1967, which are legitimate nuclear powers; on the other hand, the rest of the countries, which do not hold that legitimacy (Luiza Elena Januário, Raquel Gontijo). Moreover, even if the NPT aims at both non-proliferation and disarmament, disarmament is not actually monitored (ECPR). Therefore, nuclear powers formally committed to disarmament, but little progress has been made to date, which also contributes to the feeling of discrimination and inequality that Brazil holds (Luiza Elena Januário, Raquel Gontijo).

So, if non-proliferation and deterrence create inequality, disarmament is perceived as a logic that puts all states on the same level. 

Many Latin American states have supported, over decades, the idea that disarmament must go hand in hand with irreversibility: disarmament is perceived as permanent. Another core principle that is implicitly envisioned in this logic is good faith (Journal for Peace and Nuclear Disarmament).

Considering that the Latin American NWFZ was built upon these concepts (disarmament, irreversibility and good faith), it is possible to understand why civilian uses of nuclear technology were already foreseen in the Treaty of Tlatelolco (the NWFZ treaty for Latin America) and why they are not perceived as a threat: there is a consolidated view that nuclear weapons will not be developed; therefore, the enrichment of uranium is not directly associated with the possibility of having a nuclear weapon. 

A second reason why neither Argentina nor Brazil aims at developing nuclear weapons relies on the lack of incentives and in the evolution of their relationship. On the contrary, Argentina and Brazil have recently signed a memorandum of understanding on maritime nuclear regulation, in order to continue the cooperation in the nuclear sector and to harmonize regulation (World Nuclear News).

Rapprochement, and subsequent collaboration, between Argentina and Brazil have been ongoing for decades: they have used nuclear-related issues to build mutual trust and to create collaboration between them. The exploration of nuclear technology allowed the relationship between Argentina and Brazil to grow, and at the regional level, nuclear-related issues is what brought Latin American countries to create the first NWFZ. Moreover, Brazil aims at collaboration: it informed the IAEA, as required, in order to develop this project, and negotiations on inspections and controls are ongoing. 

Another question that raises concern is how to reconcile the spirit of the Nuclear Weapon Free Zones (NWFZ) with the use of nuclear submarines, even if they do not represent a material breach of the NWFZ treaties. The Treaty of Tlatelolco, – the NWFZ treaty for Latin America – was already foreseeing that nuclear energy could be used for civilian use. Nuclear-fueled submarines are not nuclear weapons per se. They have been used once for war-like purposes, by the UK, during the Malvinas-Falkland war, armed with torpedoes, resulting in the killing of over 300 sailors (International Campaign to Abolish Nuclear Weapons). However, the killing cannot be attributed to the fact that the submarine was fueled through nuclear energy. In any case, there are surely normative gaps related to how and when nuclear energy can be used in these borderline cases, an issue that must be solved in order not to create controversies, also considering that Argentina plans to use nuclear energy to power AI data centers.

Regarding the fact that Brazil did not ratify the TPNW, this does not mean it does not share the treaty’s objectives. Brazil considers that the TPNW should build on article VI (on disarmament) of the NPT (SIPRI), yet fewer than half of countries have ratified it (Nuclear Weapons Ban Monitor) and none are nuclear weapon states — meaning that ratifying it in the current landscape would likely deepen rather than reduce inequality among countries. At the same time, Brazil was one of the treaty’s main promoters, using its historical stance on disarmament to amplify the concerns of non-traditional powers on the international stage (Luiza Elena Januário, Raquel Gontijo), and to strengthen its case for a seat on the UN Security Council. This is consistent with Brazil’s long-standing commitment to disarmament and irreversibility, enshrined in article 21 of its federal constitution (Luiza Elena Januário, Raquel Gontijo), and with its role as the first state to propose a Latin American NWFZ (International Institute for Strategic Studies).

Moreover, the fact that the other countries in the region do not feel threatened about their developing nuclear technology is an important factor to keep in mind, since it can be taken as an indicator of the trust that Latin American states have in one another and about the development of nuclear energy for peaceful uses.

What they aim at is acquiring more power on the international stage. Not many countries have nuclear capabilities, so they are seeking to leverage this resource. 

In the current geopolitical context, nuclear energy and critical minerals are strategic assets, and both countries are working to turn their existing advantages into greater international influence.