I have, after much consideration, figured out the best way to handle the current problems with ISIS in Iraq: stay the fuck away from them. This is not our fight. This is not our problem. Yes, we broke Iraq and allowed this to occur by our severe mismanagement and misunderstanding. The people who got us into the war (George W, Cheney and others), along with their cheerleaders, like McCain, were so fucking clueless about the whole region and our place in it (ie: nowhere). McCain once famously said there isn’t any history of Shiite vs Sunni violence, which is about as ignorant as saying that in Ireland, the Catholics and Protestants have always gotten along just swell.
We don’t know what we’re doing when we go to places like Iraq. We really have no clue. The whole region got fucked up by Europe, with America nodding along, right after the collapse of the Ottoman Empire almost a hundred years ago. We continued to meddle and continued to get into more and more trouble. It got worse after Israel came along, and suddenly we had to support them always and forever no matter what they did nor how wrong it might be.
Our best bet in general is to just adopt a position of neutrality and be a lot more pragmatic in our dealings with the world. This is especially true for a part of the world where we have proven, time and again, we cannot win allies and where we have no business being.