The Submarine Development Program (PROSUB) is a partnership signed between Brazil and France in 2008, with the objective of transferring technology for the manufacture of military vessels. It is a component of the Brazil's Defense Strategy to develop the country's naval power with the production of four conventional submarines (diesel-electric propulsion) and the first Brazilian nuclear-powered submarine. The program will make Brazil one of the few countries to have nuclear technology, alongside the United States, Russia, France, the United Kingdom, China, and India.
Although the program began in 2008 with the goal of providing the Brazilian Navy with a "large naval force," it dates back to the 1970s when the Navy began seeking to master nuclear energy. In order to shorten the development time of such a program, Brazil sought partners in other countries in the hope of establishing a partnership in which technology and knowledge could be transferred for the construction and maintenance of modern submarine vessels. France was the country that made itself available for the deal, and several points were signed, which together culminate in the construction of four conventional submarines and one nuclear submarine.
In addition to the construction of the submarines, the PROSUB also foresees the construction of a complex called the Shipyard and Naval Base. This is where the submarine sections will be joined. This complex will also be responsible for installing the nuclear reactor for the first Álvaro Alberto nuclear-powered submarine. The justification given by the Navy is that it is necessary to guarantee the protection of the Blue Amazon against any attempts to claim this territory and/or its resources. According to the Brazilian Navy, submarines (especially the nuclear one) are fundamental to dissuade these claims.
The submarines coming from the program will be used to patrol the Blue Amazon and Brazilian coastal waters. Currently the first two conventional submarines (S Riachuelo (S40) and S Humaitá (S41)) are already being tested, while two others are under construction. As for the nuclear-powered submarine, the Álvaro Alberto, it will have the function of patrolling the deepest Brazilian territorial waters, since its autonomy will only be limited by the amount of supplies stored, and a replica of the nuclear reactor that will be installed in the submarine is already being tested.