Iraq is an artificial creation cobbled together from provinces of the old Ottoman Empire by outsiders. The ethnic groups and religious sects that live there were not always mortal enemies, but there was an undercurrent of enmity among them that turned malignant when Saddam Hussein imposed a murderous domination by his group, the Sunni Arabs.
When the United States waded into Iraq, it hoped that this precarious political entity could hang on in part as a barrier to Iran. After the removal of Saddam in 2003, Washington encouraged Baghdad to develop an inclusive government balancing the interests of its component ethnic groups and sects. This was a long shot from the beginning. The only chance for it to work would have been if Iraq had had a grace period of stability and economic growth, and somehow stumbled into an effective, inclusive government. Unfortunately, neither happened. Prime Minister Nouri al-Maliki’s regime simply swapped domination by a minority group for domination by the majority Shiite Arabs. Then the chaos in neighboring Syria spread to Iraq and undercut everything.
Now the chances are slim that Iraq can weather this storm and hold together. Dissolution into three parts—a Sunni Arab west, a Kurdish north and a Shiite section in the south—is so likely that American strategists should be thinking about how to respond.