Italy used the army to fight the Sicilian Mafia in the 1990s
The mafia in southern Italy has declared a "war on the state", the Italian interior minister has said.
Roberto Maroni said the local mafia, the Camorra, was trying to stamp out any opposition to its criminal power.
He was speaking after the government announced it would send 500 troops to the Campania region to help police fight local crime syndicates.
The move followed last week's killings of six Africans and an Italian near Naples which are blamed on the Camorra.
Speaking in parliament on Wednesday, Mr Maroni described the killings of the Italian national and the immigrants from Ghana, Liberia and Togo as an "act of terrorism".
He said the Italian government "must respond firmly and regain control of the region".
Mr Maroni said that was the reason why the government on Tuesday approved a three-month deployment of 500 soldiers to Campania.
The soldiers 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.
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.
Last week's killings near Naples shocked Italy.
The African immigrants 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.
The killings - which are believed to be drug related - sparked a riot by immigrants.
Police later arrested a man in connection with the shootings.