Operation Gladio was a secret stay-behind network started in Italy in 1952 , sponsored by the CIA and NATO , to organize resistance in the event of a communist takeover in Italy or a Russian invasion of other countries.

The first preparations were already made in 1947. Although the term Gladio only refers to the Italian part, similar networks in other countries are also often referred to as Gladio . Recent research has revealed that similar networks were active and linked throughout Western Europe . In any case, Gladio was active in Belgium , Denmark , Germany , France , Greece , Luxembourg , Netherlands , Norway , Austria , Portugal , Spain ,Turkey and Switzerland , while the United Kingdom and the United States also played a role in the network's strategic planning. Gladio's role in Europe , including in attacks and terrorism , has led to parliamentary investigations in various countries.

Italy
In Italy, the name Gladio first came into the public eye on August 3, 1990 when the then Prime Minister Giulio Andreotti admitted the existence of this network. He did so in testimony before a parliamentary committee investigating terrorism in Italy. Andreotti revealed that Gladio was hidden within the Defense Department with military intelligence. His statement raised suspicions that the network was involved in several bomb attacks with the aim of influencing politics.

Felice Casson , an Italian judge , had first stumbled upon the secret Gladio network while investigating far-right terrorism and forced Andreotti to give a statement. Casson discovered that the network had made connections with right-wing terrorists. The terrorists, supplied with material by the network, would carry out bombings, attribute them to left-wing Italian groups and then be kept out of the investigation by military intelligence.

Gladio's involvement has only been established with regard to the Peteano attack in 1972, which killed three members of the Carabinieri and which was attributed to the Red Brigades until 1984.

Italian judges concluded:
It is a kind of invisible government, in which the masonic lodge P2, certain branches of the secret services, organized crime and terrorism are closely linked. A dark group with extra-institutional ties has operated in our country for years with the aim of acquiring the political conditioning of democracy and personal power. To achieve its goals, this group used terrorism.