Could soldiers feel the same?

"But the image of him falling is something I'll never be able to get out of my mind. I fired, and there's Harry falling. And it was, I'd have to say, one of the worst days of my life, at that moment." - Vice President Dick Cheney

By Mr Cheney's interview it looks like he was a little depressed. Could the soldiers feel the same when they shoot an innocent person? I am glad there are some feelings which a common person like us and our leaders share.