RIO DE JANEIRO — Brazil is deploying more than 8,500 troops to the far reaches of the Amazon rain forest this month in an operation aimed at cracking down on drug smuggling, gold mining and illegal deforestation, officials said.

The troop mobilization sends a clear message ahead of the United Nations Conference on Sustainable Development, which is scheduled to take place here in June, that Brazil is taking steps to assert greater control over its porous frontiers in the Amazon. Soldiers are being sent to border areas near Venezuela, Suriname, French Guiana and Guyana.

“The Amazon is Brazil’s No. 1 priority from a strategic viewpoint, given its importance to humanity as a source of water, biodiversity and food production,” Gen. Eduardo Dias da Costa Villas Boas, chief of the Amazon Military Command, said in a telephone interview.

The operation, expected to last several weeks, showed its first results on Thursday when officials announced the detection of 10 clandestine airstrips in the state of Roraima. The airstrips were being used for illegal mining operations on indigenous territory, General Villas Boas said.