President Michel Temer has signed an executive order authorising the deployment of 10,240 soldiers in Rio de Janeiro, where violent crime is on the rise.
Brazil said on Friday that it will bolster security for next month's Olympics in Rio following the truck attack in the French city of Nice.
Brazil government has warned that it will shoot down any unidentified aircraft that violates the protected airspace around facilities of the Olympics Games.
Members of a huge police force sent to secure crime-ridden Rio before the Olympics next month have already come under gunfire, officials said as Brazil's interim president promised "absolute peace" at the Games.
The Brazilian government has not detected any threat of terrorist activity in Rio de Janeiro — the venue for the 2016 Olympic games in August, a defence officer said.