The video in this link is not for the feint hearted. It's a brutal depiction of the war in Afghanistan through the thermal sights of an AC-130 gunship. War porn to some, but I'm not showing it for that reason.
It highlights the viciousness of the conflict against IS, AQ and the Taliban. Some of those killed in that film were already wounded (note the second pass) and under old conventions would be viewed as non-combatants, and some were almost certainly unarmed from the outset. Unfortunately, when your enemy uses suicide as a tactic, the complexion of the battlefield changes, and so does your ethical compass.
Our joint police / UN compound in Jalalabad was attacked shortly after my arrival in March last year. The outer entry control point, manned by afghan police, was breached by a suicide vehicle IED (a Toyota corolla packed with HME). The subsequent assault group was spearheaded by three young men wearing suicide vests, who took out our second layer of defence, an intermediate checkpoint, also afghan police. The remaining half dozen Taliban, unable to push further, seized a strong point and fought for a couple of hours with small arms and RPGs until they were all dead. The UN section of the compound was defended by ex Gurkha contractors, who fought magnificently and did most of the damage to the attackers. The death toll at the end of the day was nine terrorists, eight police and 19 civilians. I tell you this because I had never witnessed combat like this before, and it connects with the apparent cold bloodedness of the US strike in that film. In our case the enemy cared nothing about collateral damage, had no extraction plan and no intent to surrender. Effectively, they were already dead in their assembly area. In turn, our Gurkhas and the afghan police could show no mercy, and continued to pour fire into them long after they were out of the fight.
The rules of engagement changed on 9-11. The future ain't what it used to be. This will be a very long struggle.
My condolences to the wonderful people of Paris. Our thoughts are with you.