" My dad has a story about hearing from me at work one day when I hadn’t had a chance to call in a while. He picked up the phone and was surprised to hear my voice. He was even more surprised that I was whispering. “Chris, why is your voice so hushed?” he asked. “I’m on an op, Dad. I don’t want them to know where I’m at.” “Oh,” he answered, a little shaken. "

― Chris Kyle , American Sniper: The Autobiography of the Most Lethal Sniper in U.S. Military History