Brazil is constructing five new submarines, including one atomic-powered vessel, to boost patrolling across the South American country's 8,500km coast.
The $10bn project is being undertaken by a joint venture comprising the Brazilian Navy, construction firm Odebrecht and French state-defence firm DCNS, reported AFP.
The new submarines are expected to replace the navy's existing ageing fleet of five conventional vessels.
Construction on the nuclear submarine, named SNBR, is expected to commence in 2017 with its launch targeted for 2025.
Brazil Navy official Gilberto Max Roffe Hirshfeld told AFP that the nuclear-propelled submarine is one of the weapons with the greatest power of dissuasion.
"Brazil has riches in its waters. It's our responsibility to have [a] strong armed forces. Not to make war, but to avoid war. So that no one tries to take away our riches," Hirshfeld said.
The SNBR will put Brazil in the small group of countries with nuclear submarine building capability. The others are the US, China, Russia, UK, France and India.
The 100m-long, 6,000t submarine will patrol Brazil's 'pre-salt' deepwater oil reserves and the Blue Amazon, a biodiverse region off the coast that has deposits of gold, manganese and limestone.
Work on the first submarine, which is a conventional variant called SBR1, is currently underway with 45% work completed. It is expected to be launched in 2017.
The second is in the early stages of production and could be launched in 2019.
The 75m-long and 2,000t conventional submarines are expected to be deployed to patrol ports and other strategic points along the coast.