The Atlantic's Matt Schiavenza takes a lean look at the 25 billion U.S dollars and 36,514 U.S. casualties invested in an Iraqi army of dazzling desertion rates, whole battalions of salary-drawing "ghost" soldiers, military competence purged and little to no fighting spirit, and concludes:
But the main problem with the Iraqi military is the problem with Iraq as a whole—the country effectively no longer exists as a unified state. Kurdistan, for all intents and purposes, acts as an independent country. Much of the Sunni population lives in territories controlled by ISIS. The rump Iraqi government, meanwhile, operates in close cooperation with Iran, who funds Shia militias that act as a paramilitary force. The Iraqi military, then, is less a cause of the country’s failures than a reflection of them.
Every element of Schiavenza's assessment was not only foreseeable, but foreseen. In a piece I've long since mislaid, I recall quoting, in either late 2002 or early 2003, a Kuwaiti diplomat saying to some member of the American press (I'm paraphrasing from memory): The Middle East is a sectarian powder keg and you propose dropping American firepower into it? Are you out of your Western minds?
He got that right. As bloody and fiercely depraved as Saddam Hussein's rule was, it at least held together a separable Iraq; it was an enemy of al Qaeda — ISIS' sire — and Iran alike. And George W. Bush blew it all up.
The real, "main problem" with Iraq? It is ineradicable because our history is irreversible.