The areas we call Iraq today were formerly part of the Ottoman Empire.
Under the Ottomans, the Sunnis, Shia, Jews, Christians, Kurds, all occupied various regions in common; these ethnic populations were not geographically separated. Where these different ethnicities coexisted, they each had their own religious law, religious courts, and religious police. That was how the Ottomans kept everything together, and how everybody managed to get along. It was probably the last time Mesopotamia “worked” in any political sense.
As a result of WWI the Ottoman Empire collapsed (it had sided with the Germans) and France and Britain divided the Middle East among themselves and their allies. Russia was supposed to get the part where the kurds are today, but the czar got himself knocked off and Britain wound up taking that part too.
The British called their chunk “Iraq” and imported a king from elsewhere, one with no local tribal connections, to be a suitably weak puppet monarch. They then settled in for a nice long stint of exploring, drilling and pumping (oil). However their prize turned out to be troublesome. It took a fair amount of military pressure to keep the lid on.
Held together first under imperial power and then under a sucession of local strongmen, a sense of national identity began to develop, primarily among a secularized middle class. That asset for nationalism is now pretty much kaput. Sectarian warfare is killing the middle class, pushing the middle class out of the country, and rendering the middle class irrelevant (Iraq having no economy to speak of these days).
Iraq as was is pretty much gone, all that’s left is the geography. The Iraqi moderates you’re exhorting are in a distinct minority, hunkered down and trying to survive. The best that can be done at this point would be to return to the model of governance under the Ottomans: separate arrangements for the separate sects, and a strong imperial power to guarantee the peace.
You can’t partitition the thing up into pieces without a lot of violence, because the ethnicities are too meshed geographically. Baghdad is multi-ethnic. Even pulling the Kurdish piece out of Iraq would cause a lot of violence because Kirkuk is multi-ethnic.
The outside power needed to prevent this tinderbox from exploding is going to be either Iran or the US, I don’t see any other choices. A strong central Iraqi democracy with lots of permanent US bases to project power into the region is no longer in the cards, if it ever was.
I don’t see much chance of us backing down and letting Iran fill the vacuum. Even the ‘realists’ in Washington won’t bite on that one, it’s politically untenable. Instead, what we’re going to get, whether we like it or not, is a long, slow, meat grinder. Since reconstituting the military draft in this country is not politically tenable, we can expect continued decimation of the Iraqi populace by American air power.
That’s the one bit of political flexibility the beltway boys have left: American casualties are always an issue, but it’s still politically okay in this country to kill Iraqi women and children by the thousands. We will waffle forward in this bloody fashion for some unpredictable amount of time.
Judging from the British experience, we should just get out and let the cards fall where they may. It will be for the best in the long run. The only hope for such an outcome is if the electorate in this country continues pounding on the “wise men” in Washington with a baseball bat, to make them disgorge the bad thing they tried to swallow.