Operation Gladio is undisputed historical fact. Gladio was part of a
post-World War II program set up by the CIA and NATO supposedly to
thwart future Soviet/communist invasions or influence in Italy and
Western Europe. In fact, it became a state-sponsored right-wing
terrorist network, involved in false flag operations and the subversion
of democracy.
The main function of the Gladio-style groups, in the absence of Soviet invasion, seems to have been to discredit left-wing groups and politicians through the use of "the strategy of tension," including false-flag terrorism. The strategy of tension is a concept for control and manipulation of public opinion through the use of fear, propaganda, agents provocateurs, terrorism, etc. The aim was to instil fear into the populace while framing communist and left-wing political opponents for terrorist atrocities.
See also:
Behind the Headlines: NATO's Secret Armies in Europe - Interview with Daniele Ganser
Russia versus NATO's Gladio 2.0: Turkish jihad from China to Syria
Behind the Headlines: NATO's Secret Armies in Europe - Interview with Daniele Ganser
Russia versus NATO's Gladio 2.0: Turkish jihad from China to Syria