I hang out a lot with a lot of former US infantry guys on discord, and they talk all the time about how rule one was come back alive, and rule two was 'make sure you all get your stories straight.' This mythos of the American warfighter being above and beyond is propaganda. Good propaganda, because it has some basis in truth, but it whitewashes a lot of nastiness.
The people I feel worst for are the soldiers themselves. You're informed over and over about the rules of engagement, and when you get there none of it applies.
If you don't shoot first, then your next to you friend will die. Obviously you're going to break the rules in that situation, it's what any human would do.
Now you have to live the rest of your life, knowing you broke conventions. You should be tried like the war-criminal you are. Or so it feels.
While I disagreed with the west's involvement in Iraq and Afghanistan, I have the utmost respect for the soldiers who fought there. They deserve a set of rules can realistically be followed.