Soldier aim their weapons during an operation against drug traffickers at the Complexo do Alemao slum in Rio de Janeiro, Brazil, Saturday, Nov. 27. Soldiers and police crouching behind armored vehicles trained their rifles on dozens of entrances to a sprawling slum Saturday, preparing to invade in an effort to try to push drug gangs out of an area long considered the most dangerous in Rio de Janeiro, a city set to host the 2016 Olympics.