The bombing of the Golden Mosque in Samarra, Iraq, is an ominous development for America, Iraq and the entire Middle East.
Just when it looked as if Muslims across the region were putting aside their differences to unite in protest against the Danish cartoons, the attack showed that Islamic sectarianism remains the greatest challenge to peace. It also highlighted the poor job America has done in trying to balance the interests of Shiite and Sunni Muslims in Iraq.
The shrine is one of the Shiites' holiest sites; they believe that their messiah vanished from the site, to return only on Judgment Day. Thus its destruction is a direct attack on the Shiite faith. It also symbolized the depth of Sunni rage against Shiites for having come to power in the country since the American-led invasion.
But perhaps most important, it should serve as a warning to the United States of the rising tide of Sunni extremism in the Middle East.
The postwar insurgency may have provided the arena for militants from across the Arab world to gather for jihad against America, but it is the centuries-old Sunni war on Shiism that is at the heart of the campaign of death.
A full-out sectarian war would, of course, make it impossible to create a viable Iraq. Yet for too long Washington refused to acknowledge the centrality of Shiite-Sunni antagonism to Iraqi politics. Instead, the Bush administration insisted that the insurgency was largely the work of foreign meddlers and Baathist loyalists.
As the attacks continued over months and years, Washington was finally compelled to contend with sectarian realities, yet its response was to demand that Iraqis bury the hatchet and just get along.
On Tuesday, Ambassador Zalmay Khalilzad publicly threatened the Shiite-dominated party that won the January parliamentary elections, saying that unless it formed national unity government that included Sunnis, it risked losing American financial assistance. He also insisted that politicians with ties to Shiite militias be banned from the Interior and Defense ministries.
Among the Shiites, such threats carry an ominous tone; not only because they view their militias as the only force now protecting them from car bombs, but also because Shiites see the overt American push for a national unity government as nothing more than coddling the Sunnis and, worse yet, rewarding the insurgency.
Shiites also see American policy as unduly influenced by Sunni rulers in Jordan and Saudi Arabia, who have been aggressively lobbying Washington for a greater Sunni role in running Iraq.
This has led many Shiites to talk of a "second betrayal" by the United States, a sequel to what occurred in 1991 when the Shiites rose up against Saddam Hussein only to be butchered as American forces refused to intervene.
The United States can no longer take Shiite support in Iraq for granted. The Samarra bombing led the paramount cleric, Grand Ayatollah Ali al-Sistani, to say that if the state couldn't protect them, "the believers are able to do so with the might of God."
The ayatollah, who has for three years urged restraint and calm after every car bomb and murder, seems to have reached the limits of his patience. So have his followers: His call for peaceful protest went unheeded Wednesday as Shiites attacked Sunni mosques and killed a Sunni cleric.
This American desire to placate the Sunnis could also hurt our regional ambitions. The White House has reasonable concerns about ties between Iraqi Shiites and Iran; the stated intention is to wean away Iraqi Shiites from Iranian influence.
This will not be easy to achieve in any circumstance, but will be impossible if Iraq's Shiites don't trust America's commitment to protecting their interests.
Vali Nasr is a professor at the Naval Postgraduate School and the author of the forthcoming book The Shia Revival: How Conflicts Within Islam Will Shape the Future.
The New York Times