Their motto is "Knife in the Skull." Their logo, emblazoned on the sides of their black armored vehicles and every officer's uniform, proudly displays the bloodcurdling image -- a skull with a dagger through its forehead, a pistol piercing each cheek.

Watching Rio's Special Operations Police Battalion (BOPE) storm Vila Kennedy at dawn on March 13, laden with high caliber weaponry, the word "pacification" seemed something of an oxymoron.

The troop, highly trained in urban warfare and considered one of the most efficient police squads in the world, went street to street, searching houses, cars and undergrowth for drugs and weapons.

A BOPE tractor cleared barricades of rocks and trash, presumably left to impede the entry of security forces, while helicopters circled overhead.

Vila Kennedy has been controlled by Rio's most powerful criminal gang, the Red Command, since the 1990s, while a neighboring favela, Vila Alianca, is ruled by a faction of the Pure Third Command, a splinter organization that arose in the 1980s. The two gang factions have fought bitterly for control of these communities' drug trade.

A recent surge in violence between the two sides prompted Rio authorities to push forward the planned occupation of Vila Kennedy, the latest operation in a pacification plan that has been feted around the world. The scheme, under which military police take over favelas long controlled by drug traffickers to make way for the installation of a community policing unit, is credited with bringing about a reported 65 percent drop in the murder rate of pacified areas.

Most of Vila Kennedy's criminals had in fact already disappeared or been caught before BOPE's entry -- as is standard in the pacification process, the date of the military occupation was pre-announced, and police carried out a week of operations in the lead-up. Clashes between police and criminals during this time left six people dead, including one minor, and five injured, said Rio's Security Secretariat. A total of 80 people were detained, and dozens of weapons, including grenades, automatic rifles and pistols, were seized.

A few hours into the final occupation, three more alleged criminals were picked up in a neighboring community and paraded in front of the press, alongside an assault rifle, a pistol and some bags of marijuana and cocaine.

"There are still drugs and arms here," said police commander Major Marcelo Corbage. "It will take time and the collaboration of the local population to facilitate our work."

Once BOPE has deemed the area secure -- which can take weeks or even months -- a Police Pacification Unit (UPP) will be installed, to provide permanent 24-hour community policing.

Occupation without Social Change

Vila Kennedy residents interviewed by InSight Crime all said they were pleased about the takeover, although it is important to note those who are unhappy about it are typically much less inclined to talk to the press.

"Every week there are gun battles over the hill," said Marley Slixas, 72, who has lived in Vila Kennedy for more than 40 years. "Now that the police have occupied, things are going to improve. My children used to hide scared when they heard the gunshots. Now I am hoping for a better future for them."

"We need this," said Luis Lula, an elderly man, as he sat with friends on a dusty step near a small supermarket. "People will be able to relax again."

But a key reservation was voiced again and again -- that the security forces alone could not bring about lasting change.

"We’ve always had police battalions in the community," said Valmir Cardoso. "The problem here isn’t a lack of police; the problem is a lack of social projects for the kids so they don’t grow up using or selling drugs, or doing other bad things."

Sitting in Vila Kennedy's community center following the military occupation, residents association president Jorge Melho said the favela was a vibrant community but suffered serious shortages of schools, jobs and healthcare. "We are lacking these things, that's the reality of life in the favela, and that generates violence," he said. "Replacing armed gangs with armed police will not solve our problems."

"The young people here are vulnerable; they want jobs, but if they can't find them they end up getting into crime," said Rosanede Brito Vianna, a community center volunteer. "You see them on the street sucking their thumb on one hand and holding a pistol in the other -- they are babies."

Pacification was supposed to be just the first stage of a process to bring proper public services to the favelas and integrate them into city life, said Theresa Williamson, the Brazilian-American director of NGO Catalytic Communities, which works in dozens of favelas throughout Rio.

"It was stated that the improved security would be followed by improvements in basic services like health, education and sanitation," she said. "But those services have not materialized. Instead, it's been the private sector that has arrived, installing satellite television, for example, and drastically raising prices of public utilities."

The Return of Violence

Critics point to a slew of violent outbursts in pacified favelas since the start of the year as evidence that pacification without social investment can only bring about temporary security improvements.

In Rocinha, Brazil's biggest favela and the site of Rio's biggest UPP, inaugurated in 2012, gun battles through February this year prompted the government to send in an extra 150 police.

Meanwhile, four military police have been killed in pacified favelas so far this year and more than a dozen injured in shootings, with various attacks on UPP stations. This surpasses the three killed during the whole of 2013, according to information provided to InSight Crime by the Security Secretariat. Last week, three UPP officers were shot in one night in different pacified favelas. One UPP station was completely destroyed. Including attacks in non-pacified areas, 20 police officers have been killed since the start of the year, O Globo reported over the weekend, the most recent after being shot in the throat following a confrontation with two young people on a motorbike on Saturday.

Security forces have launched deadly operations in response. Following an attack last month that killed an officer at a UPP station in Complexo do Alemao, a sprawling favela in Rio's north zone, police killed six alleged criminals in the Red Command stronghold of Juramento favela, while simultaneously carrying out other operations in Red Command-controlled areas.

On March 15, BOPE returned to reoccupy Complexo do Alemao and the neighboring Complexo da Penha in an attempt to rein in the renewed gang activity. Following last week's attacks, Rio state governor Sergio Cabral requested assistance from federal forces. "It's clear that the criminals want to weaken our policy of pacification and regain territory which for years were in criminals' hands," he said. "The state will not back down." On Monday, it was confirmed that federal troops would move in to occupy four unpacified favelas which have seen recent outbreaks of violence. 

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The attacks are "undoubtedly" a reaction by criminals to the increasing spread of the UPPs, according Rio state security secretary Jose Beltrame.

"The faction [Red Command] is finding itself trapped, with much less territory than it had eight years ago," he said. "Of course it's going to react. It's in this moment that we have to act firmly, with rationality, within the law -- everything that's the opposite of what they do. At this moment we cannot falter. (…) If we go back now, it would be an incalculable loss."

However, all the resolve in the world would not put an end to drug trafficking, he admitted. "Rio is a major consumer of drugs. Drugs enter Brazil from various place," he said. "As long as we have vice and money, unfortunately we are going to have drugs."

"Pacification was never expected to be a smooth process," said long-time Rio analyst Julia Michaels, whose Rio Real blog focuses on public security. "Police, favela residents and even criminals are learning how to behave with a new, still-evolving set of rules, both legal and societal."

Williamson, the Catalytic Communities director, said the arrival of the police and market forces without social services could only have one outcome.

"You're forcing what is already one of the most unequal states in the world to become something even more unequal, which everyone knows generates more crime and violence," she said. "That's what we're now seeing. People are frustrated; they don't have hope in the system, because what was promised has not been delivered."