I've seen some version of this question around the internet a few times over the last couple of days, mostly from conservatives but also from "hawkish liberals." As always the point is that there are bad and violent people out there in the world, so if we're not going to blow them up and arm everybody who might be inclined to blow them up, also, too, then you got nothing, do you, hippie?
No simple cause and effect with these things, ever, but we've been blowing people up and arming other people to blow people up and toppling governments and siding with the "moderate rebels" and then siding with the new moderate rebels and then the new new moderate rebels and then sometimes reconsidering and siding with the people the new new moderate rebels were attacking because those moderate rebels suddenly didn't seem too moderate anymore. Hey, where did all of those weapons go? Better send some more! Also, too, more training.
It's horrible when a lot of people get killed. Sometimes we see that, sometimes we don't.
As for what the hippies would do? Probably not quite so much blowing up. Might not work, but the blowing up isn't working too well either.
