This experience is precisely why you should never ask a war veteran if they've killed someone. Many times they have, but more often than not they've had to watch someone they were close with die.
Source: am a veteran
Source: am a veteran
https://www.google.com/search?q=how+long+has+america+been+at...
True enough, but wars tend not to last long after they lose public support (or the population 'suffers from low morale'). Having veterans speak out and seeing flag-draped coffins on the front pages tends to do that (see Vietnam), which is why modern governments try to control the war narrative ("embedded" journalism, psy-ops, etc)
I have listened when he's brought it up on his own accord, when he's been on both ends of war violence [giving it or receiving it]. They're not the prettiest images to imagine, let alone experience first hand as he did, but it's mine to listen and his to tell.