Three years after the end of World War II, the 1948 Brussels Treaty created the Clandestine Committee of the Western Union. And after the North Atlantic Treaty Organization (NATO) was created in 1949, the Western Union was left “devoid of its newly-expanded authority,” according to the University of Luxembourg.

But the Clandestine Committee was transformed into the Clandestine Planning Committee (CPC) in 1952 and, along with the Supreme Headquarters Allied Powers Europe (SHAPE), was linked to NATO. According to “The Cold War,” it was through this network that NATO member states organized the stay-behind network across Western Europe that would become known as Operation Gladio.

The CIA, with the help of MI6, was also instrumental towards setting up the stay-behind espionage networks. According to “The Declassified History of American Intelligence Operations in Europe” by Matthew M. Aid, the CIA intended to do “whatever it took” to prevent Western European countries from having any communist influence in their governments. And by the late 1960s, the CIA was “covertly financing dozens of underground stay-behind agent networks in thirteen Western European countries, including supposedly neutral Sweden.”

https://www.grunge.com/717106/operation-gladio-the-cias-secret-army-in-europe/