Paul Tibbets piloted the airplane that carried out the world’s first atomic attack, killing some eighty-thousand people, almost all of whom were civilians. His attitude towards the attack is truly disturbing, though it helps to reveal how it is people are able to carry out horrific acts of terrorism under State orders:
I felt nothing about it….I couldn’t worry about the people getting burned up down there on the ground. …This wasn’t anything personal as far as I’m concerned , so I had no personal part in it….It wasn’t my decision to make morally, one way or another…I did what I was told — it was a success as far as I was concerned, and that’s where I’ve left it…I can assure you that I can sleep just as peacefully at night as anybody can sleep….
Thicket & Thorp 
When I read that, I can unserstand more clearly why Orthodoxy has no teaching on a :just war”, and why killing, even in battle, is something we need to repent and confess.
When the conscience is dulled in such a way, one can understand the genocide of the 20th century, though of course God also had to teach Jonah that lesson.
FYI:
“Paul Tibbets and Enola Gay”
http://oliverkamm.typepad.com/blog/2007/11/paul-tibbets-an.html
Read it and learn.
Furthermore:
“More on Tibbets’s mission”
http://oliverkamm.typepad.com/blog/2007/11/more-on-tibbets.html
IMSHO, the concluding paragraph summarizes it all (for sensible folks, anyway).