My understanding of the Italian political climate of the 60s, 70s, and 80s is that there were political groups/cells (on both the far right and far left) that organized around violent acts to further their political goals (which involved the eventual authoritarian takeover of the Italian government by either the far right or far left). For example, you can think of the Red Brigades to be akin to the Black Panthers, but with actual terrorism.
In contrast, most political violence in America has been less organized and more individual-driven (e.g., see the Oklahoma City Bombing). For better or worse, the police state in the US has been quite successful in addressing and dispersing political groups that advocate for violence as a viable means for societal change.
you really try hard to see "bad commies" uh?