That ROE matrix usually presumes you're not already in a shooting war. B-17 gunners with Me-109s closing in didn't have to say "wait...let's see if he breaks into us before we know if we're cleared to shoot".
Don't mistake me: I'm not for one second advocating a "kill 'em all" ROE. But when you're in an actual shooting theater, the purpose of rules of engagement is to make sure you're shooting bad guys, not friendlies or Farmer Rasul. The chattering classes of the world want us to swoop in and arrest, with warrants and affidavits and rules of evidence, and that's not only unrealistic, but it's not required by any rules of war.
The Geneva Conventions simply don't have a category for organized, non-uniformed, armed forces of trans-national, stateless organizations. The closest category is maybe the levee-en-masse, which pretty much says you can't hang a guy as a bandit for shooting at you just because he's not in uniform. But even then, it assumes those people are operating as partisans or militia on behalf of a state. It's a huge legal grey area. Considering how long we've been fighting organizations just like that - AQ, FARC, Moros, ISIL, Red Brigades, etc - it seems past due for a change like that.
Personally, I think that if they're under arms and supporting warfare against the US, they're legitimate, legal targets. If they're inside the borders of the US, then it's a law-enforcement problem. Otherwise, fair game.
