[Nick Beale]

"In the European historical tradition intentional targeting of civilian population has been a rarity."

The history of siege warfare suggests otherwise. It appears to have been an accepted convention during the Hundred Years War for example that after a certain point (a declared number of days, say) everyone within the walls was fair game and could expect to die. I've read that under the Roman Empire a besieged city had the option of surrendering until the first battering ram touched the wall, after that it was understood that everyone was going to die.

Whole populations were massacred in mediaeval Italy, as at Cesena in 1377. The same happened in Southern France (Béziers, 1209) and thousands of civilians died in the crusader sack of Constantinople (1204). The list goes on.

If history teaches us nothing else, it is that wars quickly get very ugly indeed.