Censorship
Censorship is a dirty word that those in power want the public to ignore. America was founded on the idea of a free and raucous exchange of ideas however they may emerge so long as violence is not the end product.
Our national security state would espouse that such a free exchange of ideas is a national security threat. According to those in power, one cannot allow “extremist ideas” to propagate across the country and around the world. Such “extremist ideas” could undermine those in power and become a “threat to democracy.” Of course, such “extremist ideas” are any ideas that do not align with the prevailing ideology of those in power.