Fear is a powerful tool in election campaigns in the USA. To take up the notion that you, as a candidate, are ready to act upon undefined threats seems a crucial criterion for American voters.
Lyndon B. Johnson was the first to use, or better, feed, this feeling of fear in order to imply that his opponent was less competent in this matter. He made the political advertisement above in 1964, called Daisy girl. The interesting part I think is the incredible visual strength of the video. The images are such a powerful tool to enhance this feeling of threat and fear and translate it into two completely abstracted opposites: all that’s good and benevolent in life, the girl, and all that is evil and malevolent, the bomb.