i know it's an old argument often used disingenuously, for example frequently by the israelis, but in the precise situation of raqqa, there is no such thing as an innocent civilian, due to the support that the population was providing to isis. see, and this is actually a big part of the reason i changed my opinion about this.
i don't normally support imperialist wars, you know. i was initially opposed to this.
it's not like i didn't realize how gruesome this was going to be - and it was in fact my argument against it. religious crazies tend to regenerate, and this particular religion is tribal, and operates on revenge and blood lust. so, to win this war, you'd have to blow up entire cities - you'd have to kill sons to stop them from growing into fighters, and women to stop them from breeding. i disagreed with the experts: we could do it, but is it worth the cost? then, as more evidence mounted that isis was indiscernible from the general population, i realized that they had to be slaughtered - that the cities were going to have to crumble. this wasn't a group of extremists to contain, it was becoming a popular movement - and that's how fascist ideologies spread.
i repeat: the high civilian toll necessary to wage this war was initially the argument against it, but as the nature of the civilian population's sympathies became more readily apparent, the high civilian toll became the strategic objective. if you support fascism, you're a fascist; if you support isis, you become it. it's simply too brutal to allow for sympathies around, and any growing level of sympathy for it had to be eradicated along with it.
and, i've been absolutely clear about this - i am absolutely at war against islam, which i consider to be a fascist ideology with no redeeming qualities whatsoever; the only good fascist is a dead one. to me, the tragedy is not about dead muslims, but about the secularists and atheists that are getting caught up in it; fundamentalist muslims are valid targets here, it's the secularists that are valid civilians and valid refugees. it would be a nice to find a way to avoid killing so many of the enemy's victims.
so, this comes up against a difficult definitional problem in trying to separate between the people doing the literal fighting and a civilian population that is actively aiding and abetting it. and, so, i don't mine giving these civilians this choice: convert or die.
but, my point is that it's a tricky situation, legally. it's not clear that these are really civilian populations, or that they ought to be protected under the law - and, if they are, there is a strong argument that this ought to be an exception to it, given the support they're providing.
https://theintercept.com/2018/06/05/syria-airstrikes-isis-united-states/