KIRKUK, Iraq - Minutes after a suicide bomber killed 25 people, hundreds of angry Kurds stormed the headquarters of an ethnic Turkish group in this northern Iraqi city and torched the building and nearby parked cars.
The Kurds blamed Turkomen, the city's ethnic Turkish minority, for the bombing. Weeks later, the husks of eight burned-out cars bear witness to the ferocity of emotions generated by the crisis over who will run Kirkuk, the center of Iraq's northern oil fields.
The fate of Kirkuk, where an estimated 850,000 Kurds, Turkomen and Arabs uneasily coexist, is a litmus test for the ability of Iraq's ethnic and sectarian leaders to compromise on critical issues. At stake is the country's ability to preserve its recent decline in violence with genuine national reconciliation.
"Kirkuk is a test case for a stable Iraq," Soner Cagaptay, director of the Turkish program at the Washington Institute for Near East Policy, said Friday. "If Kirkuk remains stable, Iraq will become more stable. If Kirkuk blows up, Iraq might fracture along ethnic and sectarian lines."
The Kurds want to annex Kirkuk and surrounding Tamim province into their self-ruled region in northern Iraq.
Most Turkomen and Arabs want the province to remain under central government control, fearing the Kurds would discriminate against them.
But for the Kurds, who consider Kirkuk their ancestral capital, no issue is more important than gaining control of the province.
Rallies to press that demand have drawn thousands of people daily. It was at the beginning of one of these demonstrations, late one morning on July 28, that the suicide bomber struck. Startled protesters ran for cover in nearby buildings, some still holding up the banners and Kurdish flag, a yellow sun against red, white and green stripes.
Dozens of angry Kurds then charged the Turkomen headquarters, leaving three Turkomen injured. But U.S. and Iraqi authorities later blamed al-Qaida in Iraq - not the Turkomen - for the bombing, which killed 25 Kurds and wounded 187.
Much is at stake in Kirkuk. Without a deal acceptable to the Kurds, it will be difficult to get Kurdish cooperation on a range of issues, including a new oil law which the Kurds have blocked for more than a year.
But any power-sharing agreement must also be accepted by the Arabs and the Turkomen, the country's third largest ethnic group, if the U.S. and its Iraqi allies hope to achieve stability in the north, where al-Qaida and other extremist groups remain active.
Kurdish lawmakers blocked passage this month of a bill calling for provincial elections - a major U.S. goal - because the original legislation contained a power-sharing deal including Kurds, Turkomen and Arabs.
Nezhet Abdulgani, an official of the Iraqi Turkomen Front whose offices were attacked in the July 28 riot, warned there could be "worse days ahead" as politicians wrestle with the Kirkuk issue.
"The crisis is serious, because the Kurds can hold up any legislation they don't like, such as the electoral law," said Joost Hiltermann, Middle East director of the International Crisis Group. "It illustrates the importance of Kirkuk as an unresolved issue in undermining political progress in Iraq."
The United States and the United Nations are trying to broker a compromise. The parliament reconvenes Sept. 9 after a summer recess.
"Kirkuk is a key both for unity and division," said Mohammad al-Khalid al-Jeburi, an Arab member of the provincial council for Tamim province, of which Kirkuk is the capital. "If you turn it toward division, it could divide entire Iraq. If you turn it toward unity, then Iraq will be in cohesion."
Ethnic tensions simmer beneath Kirkuk's outward calm.
Turkomen try not to look at Kurdish police, who patrol the city in trucks with heavy machine guns. Kurds are in full control of not only the city police force, but also municipal offices and the provincial council.
There are no reliable statistics to reflect the dramatic demographic changes after the war but the Kurds now appear to make up at least half of the population, with Turkomen being the second largest ethnic group. Arabs are the third largest group and an Assyrian population is dwindling.
Neighborhoods have long been divided along ethnic lines. Turkomen, who control much of the commerce, dominate in the city center, including the ancient citadel where men play dominos in the shade to escape the stifling summer heat.
Kurds live in the northern districts while Arabs live mostly in the southern part of town.
Still, Turkish music is popular among both Kurds and Arabs. Posters of Turkish singers hang in shops in almost every neighborhood. And in a police station recently, Kurdish police were watching a Turkish soap opera.
Kurds who migrated from rural areas of northern Iraq wear checkered turbans but most others wear pants and shirts like Turkomen.
The multiculturalism masks deep-seated hostilities.
Arabs and Turkomen, who also have historical roots in Kirkuk, accuse Kurdish groups of packing more Kurds into the city to gain control in a referendum on the area's future - promised under the Iraqi constitution but repeatedly delayed.
The Kurds believe transferring the city to their control would redress the injustice they suffered when the Iraqi government launched a campaign in the mid-1970s to make the region Arab.
Thousands of Kurdish villages were razed and tens of thousands of Kurds were forcibly resettled. Thousands more were forced out during wars between the government and Kurdish separatists.
Many Kurds have returned to the area since the fall of Saddam Hussein's regime in 2003. In newly flourishing Kurdish neighborhoods, merchants hawk their wares and the streets are lined with cars.
Still, the Kurds insist many more have not returned - a charge the Arabs and Turkomen contest, insisting more Kurds have returned than were forced to leave.
"We have not been able to return half of the displaced (Kurdish) people to Kirkuk," Kurdish regional President Massoud Barzani told the English-language Kurdish paper Globe.
Turkomen and Sunni Arabs want guarantees to protect their position in Kirkuk and insist on equal distribution of seats in the 41-member provincial council in Tamim. Christian Assyrians would get 4 percent of the seats.
Ezved Rashid Salihi, the imam of the Turkoman mosque of Haci Osman in the Musalla neighborhood, accuses the Kurds of carrying out a policy of assimilation that threatens the Turkomen's future as a community.
"They have changed the Turkish name of the Delibas mosque into Dilbas in Kurdish," he said.
Iraq's 2005 constitution says the Turkoman language is official in areas where it is spoken by "a density of population."
But Sermet Salihli, who works at the Turkoman television station Turkmeneli, complains that there are no Turkish signs at government offices in the city.
The conflict has the potential to extend beyond Iraq.
Turkey, Iran and Syria have long feared that Kurdish rule of Kirkuk would encourage separatist sentiment within their Kurdish minorities.
Earlier this year, Turkey sent troops to fight Kurdish rebels waging attacks against Turkey from bases in northern Iraq.
And Turkey's next military chief, Gen. Ilker Basbug, has warned of a civil war if Iraqi Kurds seize control of Kirkuk's oil.