More than 200,000 soldiers have been deployed across Brazil to warn people about the risks of the Zika virus.
Brazil is at the centre of an outbreak of the virus, which has been linked to a surge in babies being born with underdeveloped brains.
The country has 462 confirmed cases of microcephaly, and is investigating another 3,852 suspected cases.
President Dilma Rousseff said the crisis would not “compromise” the Olympics Brazil is hosting in August.
Brazilian troops are going door to door, handing out four million leaflets advising people about the risks of the virus, carried by mosquitoes.
The BBC’s Wyre Davies, in Rio de Janeiro, says the exercise is aimed at boosting morale.
But critics have said the move would not helping reduce mosquito numbers or stop the spread of Zika, our correspondent adds.
