We don't know why Afghan troops are killing us?

Maybe because you are invaders in their country?

http://www.wired.com/dangerroom/2012/08/allen-green-on-blue/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+WiredDangerRoom+%28Wired%3A+Blog+-+Danger+Room%29&utm_content=Google+Reader