In the early years of the 20th century, the role to be assigned to submersibles was unclear and tended to be defensive. The first Brazilian submersibles lacked the range, size, and armament to contribute much beyond port defense. The very terminology–submersible rather than submarine–evokes the technological difference from modern vessels, although there is no consensus on the moment or characteristics that distinguish one from the other, and not every language makes this distinction. In 21st-century naval doctrine, the submarine is an offensive weapon, albeit one embedded within a national defensive strategy. It is "the only warship capable of operating independently, for long periods, in seas dominated by the enemy". Less dependent on logistical support and weather conditions than surface ships, it can operate alone and from the outset of hostilities. Its stealth and three-dimensional mobility allow it to strike with the advantage of surprise and inflict damage disproportionate to its own cost, although it can withstand little damage if hit. Its usual weapons–missiles and torpedoes–do not allow the destructive power to be finely calibrated to circumstances, and its very presence in a crisis area by itself exacerbates tensions. From the standpoint of international law, submarines face difficulties in rescuing shipwreck survivors and in target identification.
Anti-submarine warfare aircraft from the 1st Anti-Submarine Helicopter Squadron In both World Wars (
1914–1918 and
1939–1945), submarines found a niche in commerce raiding, sinking merchant ships to choke the enemy's maritime lines of communication. Attacks by German
U-boats on the Brazilian merchant marine were the immediate causes of Brazil's entry into both World Wars. In the following decades, the Brazilian Navy worked with the hypothesis of a
Third World War involving
Soviet submarine attacks against maritime traffic. From its
participation in the Second World War through the 1970s, Brazil adhered to the logic of collective defense of the
Western Hemisphere, within the diplomatic framework of the
Inter-American Treaty of Reciprocal Assistance. Latin American navies were to focus on anti-submarine warfare in a complementary role to the hemispheric leader, the
United States Navy. This relegated Brazil's submarines to the task of training surface forces (destroyers, the aircraft carrier
NAeL Minas Gerais and its embarked air group) in convoy escort and the identification of enemy submarines. Warfare at sea thus came to encompass three dimensions, with priority given to surface forces and missions of maritime area control. Even so, there had already been a technical capacity for offensive actions since the incorporation of
SE Humaytá in 1929; this submarine had deterrent potential, being able to blockade an enemy port through minelaying or through its mere presence in the vicinity. At least against an adversary with inferior naval power, Brazilian submarines would be employed for attack. Brazilian doctrine still recognizes possibilities in the anti-submarine domain: against opposing submarines, the Submarine Force could attack bases and control centers or be positioned in their patrol zones and along the approaches to their potential targets. Anti-submarine warfare lost priority from the 1970s onward, as the Brazilian Navy sought greater autonomy from its U.S. counterpart. The dream of the new generation of officers was a blue-water navy, centered on aircraft carriers and nuclear submarines, with full capabilities to project power and deny the enemy the use of the sea. They could point to the
Falklands War: when the
British Royal Navy, also focused on anti-submarine warfare, was forced to deal with a scenario unforeseen by its strategists, nuclear submarines proved to be its great advantage against the
Argentine Navy. The
sinking of ARA General Belgrano by the submarine
HMS Conqueror denied the sea to the Argentines, who withdrew their surface fleet to port and left their garrison on the
Falkland Islands isolated. The only Argentine warship to remain in action was the submarine
ARA San Luis, which nevertheless required considerable British effort to protect the task force.
Sea denial The traditional employment of submarines is in sea denial (SD) against the enemy, and training in this regard took place even when anti-submarine function predominated. Sea denial is one of the basic tasks of naval power in Brazilian doctrine, a list that also includes maritime area control (MAC), power projection ashore (PPA), and deterrence. The fear of a hidden submarine is a classic sea-denial option: a much larger number of defensive forces is required to protect potential targets from a small number of submarines, producing an effect disproportionate to their numbers. The mere possibility can contribute to deterrence. Under certain circumstances, submarines may be used in MAC, or even in PPA, protecting landing ships or infiltrating special operations forces. Their secondary missions also include reconnaissance and intelligence gathering. The official position in 1997 assigned equal value to SD and MAC tasks. At the turn of the 21st century, submarines were few and there was no clearly defined strategic direction. By inertia, MAC enjoyed some predominance. Some naval leaders already advocated the preponderance of SD, but the shift in mindset would have to be gradual. The 2008 National Defense Strategy (END) established a hierarchy of tasks: "in the way of conceiving the relationship among the strategic tasks of sea denial, maritime area control, and power projection, the Brazilian Navy will be guided by unequal and joint development". "The priority is to ensure the means to deny the use of the sea to any concentration of enemy forces that approaches Brazil by maritime routes. Denial of the use of the sea to the enemy is what organizes, before any other strategic objectives are met, Brazil's maritime defense strategy. This priority has implications for the reconfiguration of naval forces". "To ensure the objective of sea denial, Brazil will rely on a submarine naval force of significant scale". In the face of a superior enemy or in the early stages of a conflict, submarines, satellites, and aircraft would be the first to enter action, while surface assets would serve as a tactical or strategic reserve. Subsequent editions of the END reiterated the intention to build a substantial submarine force. The 2012 END acknowledged two strategic options: one focused on defending the coastline and
jurisdictional waters against a more dangerous adversary, prioritizing submarines, and another centered on MAC and PPA, with a balanced naval force.
Nuclear propulsion '', under construction in 2023 In the sea-denial (SD) task, the submarines historically and currently available would be best employed patrolling focal areas, with designated war or exclusion zones to keep civilian navigation away, supported by reconnaissance assets, defensive minefields, naval installations, and land-based aviation. Their limitation lies in conventional, or diesel-electric, propulsion. The speed, endurance, and stealth of conventional submarines are lower. They must periodically rise to a certain depth
–the periscope depth
–extend a snorkel to the surface, and supply air to the diesel engines that recharge its batteries. In doing so, they expose themselves to visual, acoustic, and radar detection. Below periscope depth, the vessel must conserve battery power. Consequently, its most suitable employment is in a positional or patrol strategy, not far from the coast, with adequate intelligence on the routes of enemy convoys. It effectively has a single opportunity to attack, since it can evade at high speed but must then slow down to reposition for a new attack. If the conventional submarine does not receive authorization to attack when the opportunity arises, it loses its strategic value; if it attacks without authorization, it may escalate the crisis. It can be conceived as a "mobile minefield". The limitations of the conventional submarine can be mitigated by
air-independent propulsion (AIP) technology, which has become increasingly common among 21st-century navies. AIP is not used throughout the entire voyage, but only to supplement periods of higher energy demand. The Brazilian Navy rejected this option in favor of a long-standing objective: nuclear propulsion. Since 1979 it has pursued
a nuclear program aimed at the future construction of a reactor. Brazilian 21st-century doctrine advocates a mixed submarine force, nuclear and conventional. Nuclear submarines would operate in large maritime areas, while conventional submarines would operate closer to the coast. The advantages of the nuclear submarine in blue waters diminish in the brown waters of the littoral, where the conventional submarine mitigates its weaknesses. The reactor of a nuclear submarine generates more energy and does not depend on oxygen. Beyond the positional strategy typical of a conventional submarine, it can be employed in a strategy of movement, as it does not need to snorkel and can sustain high speeds for long periods. In this way, it can accompany surface forces on the high seas and carry out successive attacks and evasions, with greater chances of survival. Compared to the conventional submarine, it is larger, has greater minimum and average operating depths, and is more expensive to build. In return, it can patrol the same area as a larger number of conventional submarines, as it spends less time on maintenance transits and inactive periods. In the English-language nomenclature, conventional submarines are designated SSK, and the nuclear-powered submarines envisioned by Brazil are designated SSN. To emphasize that the submarine will not carry nuclear weapons, the Brazilian Navy refers to its project as a "nuclear-powered conventional submarine" (
submarino convencional de propulsão nuclear – SCNA), which can be confusing abroad, where "conventional submarine" is synonymous with a diesel-electric–powered submarine. There are submarines with both nuclear propulsion and nuclear armament–the ballistic missile submarines–designated SSBN. Admiral Mauro César Rodrigues Pereira,
Minister of the Navy from 1995 to 1999, denied that a Brazilian SSBN was ever contemplated.
Geopolitical considerations At the beginning of the 21st century, a conventional naval war appears unlikely in South America, and finding a role for submarines is a difficulty shared by regional navies. The regional trend has not been toward renewing submarine flotillas. Brazilian defense documents cite material limitations, the vastness of the jurisdictional waters to be defended, and the conditions of the surrounding strategic environment to explain the focus on sea denial. This is typically the strategy of the weaker side in a naval war. Not every state has the naval power to control the ocean surface wherever it wishes, employing its war and merchant navies there. What weaker navies can do is infiltrate their submarines into space controlled by the enemy and reduce that control. This type of conflict is "littoral warfare", in which the weaker side cannot fight oceanic battles but can defend its coastline with anti-access/area-denial (A2/AD) instruments, among them submarines. In the event of war, the Brazilian Navy no longer necessarily sees itself on the "stronger side", as it did in the World Wars and the Cold War. Brazil may have to face an oceanic campaign on its own. The END mentions a "broad spectrum of combat circumstances", including situations "when the enemy force is much more powerful", which would highlight the role of submarines. Rivalry with Argentina, the possible intervention of world powers along the Brazilian coast, and the discovery of
pre-salt oil fields are historical justifications for the ambition of a Brazilian nuclear submarine. At present, it is not explained to the public in terms of a defined enemy or a need to project power, but on the basis of defending the
country's exclusive economic zone and
continental shelf–the "
Blue Amazon". External observers question to what extent patrolling natural resources is an objective suited to the capabilities of this instrument, and whether the stated objective truly reflects the Navy's intentions. The desire to possess a nuclear submarine goes beyond purely military arguments and involves institutional inertia, national pride, ambitions for technological autonomy, and the associated prestige. A nuclear submarine could project Brazilian power into distant seas, even if such ambition does not exist in current foreign policy. Its existence could narrow the gap between
nuclear and non-nuclear powers. Official language is ambitious:
Ilques Barbosa, Commander of the Navy from 2019 to 2021, spoke of a future "maximum force of strategic deterrence of our country". Debate continues over whether this ambition justifies the substantial investments required and the competition with resources for other sectors of the fleet, and the budget has proven to be the greatest obstacle to the nuclear submarine program. The promised effect will only materialize if all systems–especially weapons systems–have sufficient availability and effectiveness.
Operation zones Potential patrol zones have already been studied by the general staffs of the Navy and the Submarine Force. For the conventional flotilla, these would include the
Amazon River delta, the northeastern salient, the
ports of Salvador and
Santos, the southern coast of
Rio Grande do Sul, and other regions, according to the density of maritime traffic, oil platforms, and foreign fishing. They would extend up to 540 kilometers from the coast. In a presentation to the
Brazilian Senate in 2009, Defense Minister
Nelson Jobim used a map in which nuclear submarines patrol the limits of the "Blue Amazon", while conventional submarines occupy more internal positions, generally in oil-producing areas. The positions were hypothetical, with no defined enemy. Two focal areas for conventional submarines were proposed by a commentator in the
Revista Marítima Brasileira: one around
Cabo Frio, near the
Rio–São Paulo axis and the
Campos oil basin, and another around
Fernando de Noronha, where maritime lines of communication to the
Northern Hemisphere converge. The second area would be logistically more difficult. The Maritime Defense Strategy, a Navy planning document for the period 2024–2044, stipulates organizing submarines into a "Force of Attrition", capable of "achieving at least one of the following effects: disrupting maritime lines of communication at a port in the strategic environment; and denying the use of the following maritime areas of interest: ERG (
Rio Grande Rise); the vicinity of oceanic islands; the mouth of the Amazon River; and the
Santos and Campos oil basins". For the nuclear submarine, long mission durations would allow extensive patrols, with the caveat that its armament would not be suitable for maritime crime, which is the routine target of Navy patrols. At most, in such cases, it would alert district assets or the fleet. There is precedent–the
Ecuadorian Navy has already used the conventional submarine
Huancavilca against illegal fishing–but a large number of small patrol vessels could be acquired for a fraction of the cost of a nuclear submarine. == Number of submarines ==