Jessica T. Matthews at The New York Review of Books:
The story most media accounts tell of the recent burst of violence in Iraq seems clear-cut and straightforward. In reality, what is happening is anything but. The Islamic State of Iraq and al-Sham (ISIS), so the narrative goes, a barbaric, jihadi militia, honed in combat in Syria, has swept aside vastly larger but feckless Iraqi army forces in a seemingly unstoppable tide of conquest across northern and western Iraq, almost to the outskirts of Baghdad. The country, riven by ineluctable sectarian conflict, stands on the brink of civil war. The United States, which left Iraq too soon, now has to act fast, choosing among an array of ugly options, among them renewed military involvement and making common cause with Iran. Alternatives include watching Iraq splinter and the creation of an Islamist caliphate spanning eastern Syria and western Iraq.
Much of this is, at best, misleading; some is outright wrong. ISIS, to begin, is only one of an almost uncountable mélange of Sunni militant groups. Besides ISIS, the Sunni insurgency that has risen up against the government of Nouri al-Maliki includes another jihadi group, Ansar al-Islam (Supporters of Islam), as well as the Military Council of the Tribes of Iraq, comprising as many as eighty tribes, and the Army of the Men of the Naqshbandi Order, a group that claims to have Shiite and Kurdish members and certainly includes many Sunni Baathists once loyal to Saddam Hussein.
more here.