Most people don't want to go to foreign countries, meet exotic peoples, and kill them, as the old Vietnam-era poster put it. It's not easy to train even teenage boys to shoot people who have done them no harm. Such training, let along the actual acts, traumatize most men, and horrific numbers of them later commit suicide. More blood on your hands, George, Dick, and the rest of the gang. (Thanks to Sabine Barnhart.)

UPDATE: Writes P.M. Lawrence from Australia: "You write 'It's not easy to train even teenage boys to shoot people who have done them no harm. Such training, let along the actual acts, traumatize most men, and horrific numbers of them later commit suicide.'

"Actually, it's subtler than that. That really only happens when people have to kill people they identify with. In western cultures, that applies to most potential killers and to most potential targets, but the historical norm is killing the 'other', which is quite easy and doesn't have those repercussions. The difficulty comes from having to unlearn or override our own norms, ones which we learned while growing up; these difficulties are learned, not inherent. For an example of different cultural behaviour, just look at Uganda's 'Lord's Resistance Army'".