A young cowboy from Texas who joined the elite US Navy Seals became the most deadly sniper in American history. In a book published this month he provides an unusual insight into the psychology of a soldier who waits, watches and kills.



As US forces surged into Iraq in 2003, Chris Kyle was handed a sniper rifle and told to watch as his marine battalion entered an Iraqi town.



A crowd had come out to greet them. Through the scope he saw a woman, with a child close by, approaching his troops. She had a grenade ready to detonate in her hand.



"This was the first time I was going to have to kill someone. I didn't know whether I was going to be able to do it, man, woman or whatever," he says.