Courtesy of This American Life I think. On WGBH, 90.9 FM Boston. Listen to it now if you can. Catch a recording online if you can't. But seriously, listen to it.
tl;dr According to the interviewee, military training is a form of temporary, induced sociopathy. And it's less temporary for some people than for others.
Seriously: listen to it. Then we'll talk about the possible repercussions.