Fear is America’s top-selling consumer product
To be honest I think this was pretty obvious to anyone living outside the US, especially after 9/11. And unfortunately for the rest of the world, it's nothing US exclusive, scaring people into obedience is the oldest trick in the book. Fear has been always one of the main selling point for politicians, ever since the beginning of time. When faced with a common threat (real or not) people tend to unite under a leader who they hope will protect them, and it's any totalitarian ruler's wet dream. Frightened people are easier to control and far more likely too look the other way on whatever irregularity or injustice, as it will always seem unimportant compared to the threat and fear they feel.