>>64461788
They did that in the past, in 2010 there was a large operation with the involvement of the brazilian army, marines and a federal unit that is like a National Guard.

It led to the establishment of what were essentially small FOBs (or COPs) inside the favelas where regular police would be stationed for the long term, the thing is that during the operation most criminals managed to flee through those jungle areas, so later when the armed forces went home and only the regular cops were left behind, the criminals returned and they either struck deals with the cops or straight up intimidated and things went back to what they were previously essentially.

Also the army has a lot of the failings of a peacetime army, training is not that great, they did not perform any better than the police forces, the only thing they could bring to the table are the M113s armored vehicles and AAVs (yes those ones), but they are of limited use inside the favelas and only were used to cordon off the area (but because of limited mobility only the city side, the jungle area was left open).