A diplomatic revolution in the Middle East?

Back in 2001 the problem seemed clear. Al-Qaeda and the Taliban were Sunni extremist groups. It was a stretch to broaden the idea to encompass the Sunni secularist Saddam Hussein, but it was clear enough that the U.S. had been attacked by Sunni Muslims. It made sense at the time when you heard rumors of cooperation between the U.S. and its longtime antagonist, the Shiite Islamic Republic of Iran, against the Taliban and al-Qaeda. But George W. Bush muddied the narrative by vowing enmity to an Axis of Evil that included Iran, and it became part of our strategic mission in Iraq to deny Iran the influence there, post-Saddam, that was arguably inevitable given the Shiite majority in both countries. Regardless of what Bush or Obama hoped for, the al-Maliki government leaned toward Iran while practicing Shiite chauvinism at home. The reaction at home is the ISIS uprising, the resurgence of militant if not terrorist Sunnism. The reaction abroad to that includes new rumors of cooperation, if not rapprochement, between Iran and the U.S. The U.S. denies any desire for military cooperation while Iran denies any current plan to intervene militarily against ISIS. But once again the two antagonists see a common enemy. That should be enough to get something accomplished, if either country is willing to apply muscle or money and neither expects or demands too much. The problem last time was the Bush demanded far too much, actually aspiring to an "end to evil" that meant the end of the Islamic Republic. Make no mistake: the Islamic Republic has done some evil shit just as just about every country has done. Their governing doctrine is abhorrent to anyone who values democracy, civil rights and secularism. But if Churchill and Stalin can ally against Hitler, it shouldn't be so hard for the U.S. and Iran to work together against a form of Islam arguably worse than anything Iran promotes. On top of hating all infidels, Sunni extremists like ISIS hate Shiism as a form of idolatry. They are enemies of civilization in ways the Iranians are not. No two groups should have to agree on everything or anything else to agree that Sunni extremism needs to be deterred if not stopped outright. Cooperation in Iraq might set the stage for at least negotiations toward a settlement of larger conflicts between Shiism and Sunnism, to the extent that those drive the civil war in Syria and conflicts elsewhere. Expecting it to promote settlement of the major issues between Iran in the U.S. is too much to ask. Cooperation should not require us to acquiesce in Iran's acquisition of nuclear weapons, nor Iran to make peace with Israel or whatever else might please the U.S. Those are topic for other times, but Americans are dangerously impatient with diplomacy. This would be a time for American diplomats to be more patient and more focused on immediate problems. If the conquest of Iraq by ISIS is as undesirable as everyone seems to think, preventing it by with as few bad consequences as possible should be every nation's priority.