In view of the challenge represented by advances in the nuclear field—and with the PROSUB Program as its greatest milestone in technological and strategic development—on September 5, 2025, Brazil’s Minister of Mines and Energy, Alexandre Silveira, publicly declared the need to expand nuclear capabilities for long-term military purposes, with the aim of strengthening national defense and consolidating Brazil’s regional projection. Days later, the ministry issued a clarifying note to address the interpretations and speculation that arose following the minister’s statements to the press:
“The Minister of Mines and Energy, Alexandre Silveira, a jurist and pacifist, reaffirms that the use of nuclear energy in Brazil can only have peaceful purposes, as determined by the Federal Constitution. Therefore, it must be used for the generation of clean electricity and for its application in nuclear medicine, both for diagnosis and for the treatment of diseases.” (Ministry of Mines and Energy, 2025 as cited in Assis, 2025)
Although the explanations were justified, the regional and international nuclear agenda experienced a profound shock to its foundations, in a general context of growing geopolitical tensions, armed conflicts, and increasing military spending among the major powers. For Brazil, this shift in its approach to nuclear energy could affect not only its ongoing maritime technological and industrial development programs but also its international relations.
The Submarine Development Program of the Brazilian Navy, commonly known as PROSUB, was established in 2008 with the objective of building and acquiring four conventional Scorpène-class (S-BR) submarines and one nuclear-powered submarine (SN-BR), along with a new Naval Base to host them and the necessary infrastructure for their operation.
The recent public statements appear to question the nuclear component of Brazil’s historic program: unlike conventional submarines, powered by diesel-electric transmission, nuclear-powered submarines (SSNs) feature specially designed modular reactors, specifically called pressurized water reactors (PWRs), to generate energy. The transition to nuclear propulsion systems ensures stealthy mobility at higher speeds and eliminates the need for short-term refueling.
For the purposes of this article, the application of nuclear propulsion systems is limited to naval platforms. The first international experiences date back to 1955 with the U.S. submarine USS Nautilus; its development spurred the construction of the Skate-class and the first nuclear-powered aircraft carrier, USS Enterprise.
The use of nuclear propulsion in military vessels also extended to conventional icebreakers in the Russian Navy: the Lenin was the world’s first of its kind in 1959, followed by the Arktika-class in 1975. Likewise, civilian merchant ships were fitted with nuclear propulsion technology but proved economically unsustainable. Among these units were the U.S. NS Savannah, the German Otto Hahn, the Japanese Mutsu, and the Russian NS Sevmorput (World Nuclear Association, 2025).
As of 2024, the P5 + India countries concentrated a total of 130 nuclear-powered submarines: internationally, the United States, France, and the United Kingdom maintain fleets entirely composed of nuclear-powered submarines, with 66, 10, and 10 units, respectively. In hierarchical order: the United States, Russia (31 units), China (12), the United Kingdom, France, and India (2) (Buchholz, 2024).
Currently, most countries possessing these technologies have increased modernization programs. For example, the U.S. Navy’s Virginia-class is in active development, with 23 units incorporated to replace the 1985 Los Angeles-class. For Russia, one of its latest active projects, the fifth icebreaker of Project 22220, Chukotka, began construction in late 2020 and is expected to enter service in late 2026. Likewise, in November 2024, the third Suffren-class submarine, SSN Tourville, was commissioned into the French Navy.
Only six countries in the world currently operate SSNs, with the gradual incorporation of Australia and Brazil into the group of states controlling sensitive nuclear propulsion technology. Comparatively, Australia and Brazil are non-nuclear-armed states acquiring SSNs—Australia under AUKUS, and Brazil through a joint partnership with France. The Treaty on the Non-Proliferation of Nuclear Weapons (NPT) is complemented by IAEA Safeguards Agreements, which include provisions for loosely regulated or unregulated areas, such as the use and handling of enriched uranium for non-proscribed military activities under the treaty. Essentially, most of these vessels employ highly enriched uranium (HEU) to fuel modular nuclear reactors. The issue becomes complex because HEU is also a key material for manufacturing nuclear weapons and explosive devices. Its dual-use nature—for peaceful or military purposes—heightens the risk of diversion, particularly from ostensibly peaceful or scientific nuclear programs toward military applications. Paragraph 14 of the IAEA’s INFCIRC/153 sets a regulatory framework to verify the use of nuclear materials in non-proscribed military activities when safeguards agreements do not apply.
PROSUB as a pillar of technological advancement and Brazil’s maritime projection
The construction of Brazil’s SSN Álvaro Alberto adheres to INFCIRC/153, confirming that developing nuclear propulsion systems is a non-proscribed military activity under the treaty and does not involve the production of nuclear weapons or explosive devices.
Brazil possesses three natural uranium deposits, sources of the raw material used in nuclear reactors: Poços de Caldas (Minas Gerais), Santa Quitéria (Ceará), and Lagoa Real or Caetité (Bahia), the latter operating since 1999 and owned by Indústrias Nucleares do Brasil (INB) (World Nuclear News, 2024). Internationally, Brazil is subject to IAEA inspections on its nuclear material inventories, records, facilities, and containment and surveillance measures. It is worth noting that by 2022, the country held 5% of the world’s uranium reserves, along with enrichment plants (Merino, 2023).
Based on its national capabilities, Brazil is responsible for developing the propulsion reactor and nuclear fuel for its submarine unit. Under the PROSUB framework, France will provide technology transfer, technical assistance, and training in the design, manufacturing, construction, and operation of Brazil’s first SN-BR (Elizondo, 2025). The program marks a new stage in bilateral industrial and maritime cooperation between the two nations. In 2000, the Brazilian Navy acquired the aircraft carrier NAe São Paulo [A-12], formerly the French Clemenceau-class Foch, which remained in service until 2018 and was dismantled and sunk in 2023.
According to OSINT StratBridge, of the four conventional Scorpène submarines renamed the Riachuelo-class under the Brazilian program, the SBR Riachuelo [S-40] entered active service in September 2022, and SBR Humaitá [S-41] in January 2024. The SBR Tonelero [S-42] was launched in March 2024, and the final unit, SBR Almirante Karam (ex Angostura) [S-43], is under construction to be launched in 2025.
The Riachuelo-class submarines are built, assembled, and launched by Itaguaí Construções Navais (ICN) with Naval Group providing technical and technological transfer. They feature an extended hull (71.6 m), larger crew capacity (35 personnel), and greater autonomy (70 days), meeting Brazil’s operational requirements. These multipurpose units are capable of reconnaissance, special operations, anti-submarine warfare, and anti-surface warfare. They are equipped with SUBTICS combat systems, six F21 torpedo tubes, and SM39 Sub Exocet missiles. Another South American operator of Scorpène-class submarines is Chile, which acquired the O’Higgins [SS-23] and Carrera [S-22] in 2005 and 2006, respectively.
In parallel, Naval Group is also part of the consortium building Brazil’s first conventionally armed, nuclear-powered submarine, the Álvaro Alberto, measuring 100 m in length, 9.8 m in beam, with 6,000 tons of displacement and a crew capacity of 100. As the four Scorpène-class submarines progress—Phase I of the program—on June 12, 2025, the Brazilian Navy began cutting the first steel plate for the fifth submarine at the Itaguaí Naval Complex (Phase II). Construction of the submarine’s reactor is underway at the Aramar Experimental Center, under the LABGENE (Nuclear Power Generation Laboratory) project—a prototype of the future nuclear reactor for propulsion. Since June 2025, Naval Group has provided engineering, assembly, and construction services for the Controlled Auxiliary Building of LABGENE.
The public statements by Minister Silveira strain this comprehensive regulatory framework: the ambition to develop nuclear weapons would violate Brazil’s regional and international commitments dating back to 1967, as well as Article 21 of its Federal Constitution. Nuclear material would shift from a peaceful input to a weapons precursor—a clear diversion from its original objectives.
As various control mechanisms over arms, technology, and nuclear-use materials exist, the nature of nuclear programs reflects a state’s national interests and its intended projection of power. Thus, it is pertinent to ask: How will the IAEA ensure compliance with international nuclear law? What repercussions will this have on Brazil’s foreign relations?
Brazil stands out as the only Latin American country pursuing a state policy for the comprehensive reform and modernization of its maritime capabilities. Alongside PROSUB, the Tamandaré-class Frigate Program (PFCT) is advancing, providing essential surface fleet assets, alongside other domestic and international acquisitions. Through these ongoing projects, Brazil reaffirms its status as a regional maritime power, pursuing objectives of sovereignty and defense-industrial prosperity. The challenge of managing and protecting the 5.7 million km² of the “Blue Amazon” has driven the acquisition of new means to deter threats to its territorial integrity and natural heritage.
In contrast, despite its extensive naval history, Argentina currently lacks a submarine acquisition or modernization program. Since the loss of the ARA San Juan [S-42] in 2017, the Navy has had no operational submarines. Its two remaining conventional units are inactive due to technical issues. According to StratBridge, the ARA Santa Cruz (TR-1700), built by Thyssen Nordseewerke in 1982, last sailed in June 2014 before entering Tandanor shipyard, where it remains since the suspension of repairs in 2019. The ARA Salta (Type 209-1200), in service since 1974, also carried out its last navigation in 2014, and since that year it has remained moored at the Mar del Plata Naval Base; it is currently used as a training platform for future Navy officers, but without immersion or navigation capability.
As regional neighbors, Brazil and Argentina share asymmetrical experiences. The projection of their defense and industrial development policies has reached certain common turning points and changes of course throughout the second half of the 20th century. From 1913 to 1989, the Brazilian Navy acquired various classes of submarines from international shipyards, originally Italian, American, British, and German. Indeed, the first Tupi-class submarine of the German Type 209-1400, the Tupi [S-30], was built at the Howaldtswerke Deutsche Werft (HDW) Shipyard in Germany and incorporated in 1989. Starting in the 1980s, with an active contract with HDW, Brazil’s naval industry boosted its capabilities in the manufacturing of submarine units.
Commissioned by the Arsenal de Marinha do Rio de Janeiro, the Tamoio [S-31], Timbira [S-32], and Tapajó [S-33] were delivered to the Navy in 1994, 1996, and 1999, respectively. The Tikuna [S-34], of the Tikuna class — an improved German Type 209-1400 Tupi — was the last submarine built by the local Arsenal and was incorporated in 2005.
PROSUB materializes the decisive evolutionary pace of Brazilian industry and defense. The National Defense Strategy, established that same year, formalized the objective of acquiring and constituting a “Large-Scale Naval Force” (Marinha do Brasil, 2022), strengthened by modern maritime capabilities. The 1980 Brazilian project was formally integrated into the national production framework with the construction of four conventional Riachuelo-class submarines and, most notably, the nuclear-powered submarine.
By contrast, the Argentine program did not achieve the same positive results. The Argentine Navy commissioned the German shipyard Thyssen Rheinstal Technic to develop two fifth-generation TR-1700-class units, the ARA Santa Cruz [S-41] and ARA San Juan [S-42], incorporated in 1984 and 1985, respectively. The contract stipulated the construction of four additional units of the same class in Argentina. Thus, in 1978, construction began on the Ministro Manuel Domecq García S.A. Shipyard in the port of Buenos Aires, completed in 1981. Argentina established milestones in its submarine program, qualitatively surpassing its regional neighbor Brazil: by 1985, it possessed the most advanced conventional diesel-electric and snorkel-propelled submarines of its time, in addition to the only submarine shipyard in the Latin American region (Olivera, 2017).
The construction of the ARA Santa Fe [S-43] and ARA Santiago del Estero [S-44] units took place in parallel with the beginning of the Tupi-class development in Brazil. However, in 1989, the fate of Argentina’s TR-1700 class was sealed: the works were halted, leaving two unfinished projects with approximately 50% and 30% progress, respectively. During President Carlos Menem’s administration, the Domecq García Shipyard was sold in 1996, and the unfinished units were dismantled to provide spare parts for the submarines in service. Without a mother shipyard for submarine maintenance and overhauls, the ARA Santa Cruz was assisted by the Rio de Janeiro Naval Arsenal between 1999 and 2001, while the ARA San Juan underwent a mid-life modernization process between 2007 and 2014 at the currently named Almirante Storni Shipyard (formerly M.M. Domecq García).
Without the necessary naval assets, Argentina’s maritime deterrence will remain an unresolved issue. Since November 2024, the Argentine Navy has been evaluating the decommissioning of the ARA Santa Cruz, which has been at the Almirante Storni Shipyard since 2014, and the scrapping of the unfinished TR-1700 sections. The ARA Salta is expected to share the same fate. Considering these losses, the letter of intent confirmed during the same period by the national government with Naval Group for the acquisition of three Scorpène Evolved submarines could once again boost defense planning.
Had the TR-1700 program been completed, Argentina would have had six conventional diesel-electric submarines—additional to the Type 209s—with the potential to replace their propulsion system with a nuclear-powered one (Patrulleras Argentinas, 2011). The common aspiration shared in the 1970s and 1980s for the acquisition of SSNs ultimately produced a clear winner. According to current facts, the balance continues to favor Brazil.
Its state policy and long-term projection correspond to its national industrial and technological capabilities, but fundamentally, they respond to two essential objectives: to guarantee and safeguard national sovereignty, and to strengthen its geopolitical position regarding the Blue Amazon and its strategic international relations. Quantitatively and qualitatively, Brazil surpasses the maritime capabilities of the region, which, through perfect synergy between its political, economic, and industrial elements, has achieved successful outcomes in favor of national defense and security.
*Article written by Valentina Angaramo Berrone.
Bibliography consulted:
Assis, M. (August 9, 2025). Ministro explica que fez defesa de energia nuclear, mas só para fins pacíficos. g1. Retrieved September 10, 2025.
Buchholz, K. (September 4, 2024). Only Six Countries Operate Nuclear Submarines. Statista.
Elizondo, S. (June 19, 2025). Los submarinos de propulsión nuclear de Australia y Brasil. Caminos diferentes y desafíos compartidos. Observatorio Estratégico de los Marea de China. Universidad de la Defensa.
El Snorkel. (November 1, 2002). El programa de construcción de Submarinos en Argentina.
Marinha do Brasil. (5 de septiembre de 2022). Submarinos (Classe Riachuelo). Updated October 20, 2022.
Merino, A. (November 2, 2023). El mapa de las reservas de uranio en el mundo. El Orden Mundial.
Olivera, J. P. (September 8, 2017). Argentina tiene dos submarinos en un galpón. Zona Militar.
World Nuclear Association. (February 4, 2025). Nuclear-Powered Ships.
World Nuclear News. (August 22, 2024). Brazil to resume uranium exploration.
*Images used for illustrative purposes.
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