During the 60's and early 70's, during the Vietnam War, they used to blow the air raid signal every Wednesday night at 7pm, I guess to make sure it worked and to make sure people knew the difference between that and a regular fire alarm.
It's very scary. I can't imagine what the people of Iraq are feeling right now. Some joy, some fear, some hope, some sorrow, some happiness, some sadness, some dread, some love, some hate. It must be awful.