CONSPIRACY Believing is Seeing

When a fugitive is being tracked by the government in a movie, you frequently see a black helicopter following them. And if you are ever on the run and see one, it might not be all in your imagination; several government agencies use Black Helicopters for covert operations and also at night without lights for both training and live missions. Black helicopters are used as a symbol of an inevitable military takeover of the United States in the American militia movement, and sightings have been linked to cattle disfigurement.

https://en.wikipedia.org/wiki/Black_helicopter