People have always used fear for intimidation of the subordinates or enemies, and shepherding the tribe by the leaders. Recently, it appears that Pres. Trump has used fear by suggesting in a tweet that four minority congresswomen go back to the places they came from.
There is a longstanding history of employing the fear of “the others,” turning humans into illogical ruthless weapons, in service to an ideology. Fear is a very strong tool that can blur humans’ logic and change their behavior.