Operating in all of NATO and even in some neutral countries or in Spain before its 1982 adhesion to NATO, Gladio was overseen by the SHAPE (Supreme Headquarters Allied Powers Europe), transferred to Belgium after France’s official retreat from NATO — which was not followed by the dissolution of the French stay-behind paramilitary movements.
A second secret army command center, labeled Allied Clandestine Committee (ACC), was set up in 1957 on the orders of NATO's Supreme Allied Commander in Europe (SACEUR), based in NATO's Supreme Headquarters Allied Powers Europe (SHAPE) in Mons, Belgium. The ACC's duties included elaborating on the directives of the network, developing its clandestine capability, and organizing bases in Britain and the United States. In wartime, it was to plan stay-behind operations in conjunction with SHAPE. According to former CIA director William Colby, it was 'a major program'.
Coordinated by the North Atlantic Treaty Organization (NATO), the secret armies were run by the European military secret services in close cooperation with the US Central Intelligence Agency (CIA) and the British foreign secret service Secret Intelligence Service (SIS, also MI6). Trained together with US Green Berets and British Special Air Service (SAS), these clandestine NATO soldiers, armed with underground arms-caches, prepared against a potential Soviet invasion and occupation of Western Europe, as well as the coming to power of communist parties. The clandestine international network covered the European NATO membership, including Belgium, Denmark, France, Germany, Greece, Italy, Luxemburg, Netherlands, Norway, Portugal, Spain, and Turkey, as well as the neutral European countries of Austria, Finland, Ireland, Sweden and Switzerland.
The existence of these clandestine NATO armies remained a closely guarded secret throughout the Cold War until 1990, when the first branch of the international network was discovered in Italy. It was code-named Gladio, the Latin word for a short double-edged sword (gladius). In Belgium, the secret NATO army was code-named SDRA8, in Denmark Absalon, in Germany TD BJD, in Greece LOK, in Luxemburg Stay-Behind, in the Netherlands I&O, in Norway ROC, in Portugal Aginter, in Switzerland P26, in Turkey Counter-Guerrilla, in Sweden AGAG (Aktions Gruppen Arla Gryning, and in Austria OWSGV. However, the code names of the secret armies in France, Finland and Spain remain unknown.