Italy used the army to fight the Sicilian Mafia in the 1990s
Italy will send 500 troops to the southern Campania region to help police fight the local mafia, the government has announced.
The move follows the killings of six African immigrants and an Italian near the city of Naples last week.
The killings - which sparked a riot by immigrants - are blamed on the local mafia, the Camorra, and are believed to be drug-related.
On Monday, police made their first arrest in connection with the killings.
Police say they are still looking for two other people.
The immigrants - from Ghana, Liberia and Togo - were attacked by gunmen last Thursday in the town of Castelvolturno, near Naples.
Shortly before, gunmen shot dead the owner of a games arcade in the same town, firing 60 bullets into his head and stomach.
Italian Interior Minister Roberto Maroni announced a three-month deployment of 500 soldiers to Campania after a cabinet meeting.
They will join an extra 400 police and paramilitary carabinieri who have already been deployed in an effort to break the Camorra's stranglehold on its heartlands around Naples.
Mr Maroni said that strengthening local police with troops had had "excellent results" in the past.
The government will be hoping that the move sends a clear message of intent to the crime syndicate in Campania, the BBC's Mark Duff says.
But the culture of Camorra criminality runs deep, offering its own social network, sense of community and jobs of a kind - mainly involving cigarette-smuggling, drugs and petty crime, our correspondent says.
This is the second time since the 1990s that the army has been ordered to join the fight against organised crime in southern Italy.
Some 150,000 soldiers were sent to Sicily in 1992, following the murder there of two leading anti-Mafia judges.