Unfotunately you've just given us a good example of a situation where there aren't any rules of conflict, namely the genocidal forever war against Palestinians. Never mind white phosphorus, the rules say you can't occupy territory indefinitely, can't build settlements on occupied land etc etc.
Erm, yes, that was my point. There are rules, and sometimes those rules do get broken. Some countries/armies don't 'play by the rules' which is indicative that the civilian population, hospitals, schools, places of worship, ceasefires on humanitarian evacuation routes, journalists are considered fair game and so it's not a 'red herring' to address the issue of what type of weapons are being used and where, because in that kind of situation, the situation is worse - if that's imaginable.
Some people seem to be putting words in my mouth and projecting on me a kind of attitude of 'that's all right then' regarding the use of conventional weapons against civilians. No, of course it's not all right, ffs. I mean, I've been on urban for more than a decade now, and shouldn't have thought I'd have a reputation as a right-wing neolib who eschews morals and legalities when it comes to humanitarian causes and crises. So does what's being projected onto me track with my track records on these boards?
The type of weapon being used and where is highly relevant in that use of these non-legitimate weapons - NB: I didn't make the rules, didn't write the Geneva Convention - means that what's already a fucked up situation is inestimably worse for civilians, the risks they face to their lives are much higher than they would otherwise be.
My point is that it's not irrelevant, and it's not a matter of 'that's all right, then' if only conventional weapons are used, it's that if/when these other weapons are used it's indicative that all bets are off and things like war crimes and genocide are now afoot, where civilians aren't just 'collateral damage' but actively targeted, and the humanitarian crisis is going to be much worse and, no, by pointing that out that doesn't mean I think that's all right, in fact I think the opposite. Sheesh.