In one of several military operations that have been launched over the past year to tackle illegal gold mining, illegal deforestation and drug smuggling in the Amazon rain forest, Brazil is sending more than 8,500 troops to patrol an area that stretches across the northern border of the country.

The deployment, which underscores Brazil’s efforts to assert greater control over the more than two-thirds of the Amazon that falls within its borders, comes as international expectations over Brazil’s role as a regional power rise -- and as a United Nations conference on sustainable development to be held in Rio de Janeiro nears. ...