Strangely enough, dozens of soldiers from elite Brazilian military units, as well as members of special operations forces from around the world, vie each year for coveted spots in the courses at the center, which is emerging as a cornerstone of Brazil’s ambition to spread its influence into parts of the developing world, especially in Latin America and Africa.

In courses lasting about nine weeks, instructors submit soldiers to an array of punishing tasks. The soldiers must endure long hikes through the jungle, swim in waters infested with caiman and piranha and survive for several days without rations, hunting or foraging for their own food.

Instructors also deprive soldiers of sleep, roaring insults at them when they show signs of fatigue, and force them to engage in hand-to-hand combat with one another. Throughout it all, soldiers rest (when permitted) in hammocks pitched on trees deep in the forest, where they are often soaked by heavy rains or bedeviled by the ear-piercing groans of howler monkeys.

“It has been a very, very hard and tiring experience,” said Lt. Djibil Toure, 26, one of four junior officers from a special operations unit in Senegal’s army sent to take part in the course this year.

The Senegalese contingent dropped out after failing a test in which participants must tread water in full gear, carrying backpacks and a rifle that together weigh more than 100 pounds. But they remained here as observers because Brazil has agreed to help Senegal’s army improve its jungle warfare abilities.