This is only because we and our allies don't face an existential threat from our adversaries. It'd likely be much more effective to, say, ruthlessly hunt down a

This is only because we and our allies don't face an existential threat from our adversaries. It'd likely be much more effective to, say, ruthlessly hunt down and murder the extended families and friend networks of known terrorists or insurgents to discourage terrorism and uprisings, but the diplomatic cost of such actions in what amount to wars of choice is too high, and it would do too much damage to our narrative of "good guys versus bad guys". We're bad at fighting these types of groups because we choose to be bad at it, because the narrative matters more than winning—the cost of losing, or at least of a perpetual draw, isn't nearly as high as the cost of winning using effective but brutal strategies. In a "real" war, that likely wouldn't be true. Give us an actual threat and we'll go right back to flattening cities and firebombing civilians in no time. (note: I'm not advocating these tactics, I just think our relative restraint is a consequence of our position in current geopolitics, not of some ethical enlightenment on our part)