With the overthrow of Saddam Hussein, Iraq's ethnic Kurdish minority has achieved a long-held dream: restored control over broad swaths of territory the Kurds consider their own. But as the U.S.-led war that toppled the Iraqi president comes to an end, Arabs, Turkmen, Americans and the Kurds themselves are struggling to prevent that dream from becoming a nightmare.

The new map of Iraqi Kurdistan is being drawn with politics, blood and ethnic conflict. Northern Iraq is seething with tension between Kurds and other ethnic groups. The two main Kurdish political parties are at odds over how to administer the north. And U.S. forces are trying with mixed results to balance the various factions while a new, post-Hussein Iraq takes shape.

The outlines of the conflict are visible on the walls of mud huts in Muntasir, a hamlet a few miles south of Kirkuk, the region's oil capital. Muntasir is an Arab village, created in the aftermath of a failed Kurdish revolt in 1975 as part of Hussein's program to expel Kurds from the area and replace them with Arabs.

On Tuesday, however, Kurds from the neighboring village of Indijah came to Muntasir and told the Arabs they had 24 hours to leave. Across the fronts of buildings in the hamlet, Kurds scrawled the initials of the Patriotic Union of Kurdistan (PUK), one of two militia-backed political parties in the north. The names of Kurdish peasants were written on three houses that they evidently planned to occupy.

"We are defenseless," said Hamad Oweid, an Arab shepherd and father of five daughters. "Many families left to hide in the mountains. We don't know what else to do."

In Kirkuk, meanwhile, the city's two new de facto mayors are taking a more measured approach to ethnic tensions.

One of the men, the PUK's interior minister, Faraidoon Abdul Qadir, listened to an ethnic Turkmen couple who had been told by Kurds that they must give up their home. He sent them away with a security squad to confront the ruffians. The other mayor, Kamal Kerkuki, a native of Kirkuk and member of the political bureau of the rival Kurdistan Democratic Party (KDP), said the people who have poured into Kirkuk since it was liberated -- including Kurds displaced by Hussein's Arabization campaign -- have been told to leave. Property disputes will be settled by judges, he said.

"Now everybody who came from outside must go out," Kerkuki said. "The population of Kirkuk will decide who is powerful in the future."

From the region's dusty villages to its halls of power, there are countless examples of how the war has overturned decades of Kurdish misfortunes. But the war has also left key questions: Can Arabs, Turkmen and Kurds live together peacefully after years of bitter warfare? Will the Kurds be allowed to retain control of key northern cities and the lucrative oil fields in this impoverished region? And if so, can the Kurds create order and a measure of prosperity out of a chaotic situation?

The conflict between Kurds, Arabs and Turkmen in northern Iraq predated the U.S.-led war and could last well beyond it. Earlier Kurdish drives for independence, expanded autonomy and territory have been powerful fissures in Iraqi political life.

For many years, the PUK and KDP held almost no territory and were pursued relentlessly in mountain refuges by Hussein's armies. It was only after the 1991 Persian Gulf War and the failed Kurdish uprising that followed that an autonomous region took shape, existing outside government control and protected by U.S. and British planes enforcing a "no-fly" zone over northern Iraq.

Hussein's government maintained control of Kirkuk, Mosul and the rich northern oil fields, however -- until last week. With the collapse of Iraqi authority, the PUK sent its forces to Kirkuk without U.S. permission, a breach of an agreement to keep its militia under U.S. command. Looting and mayhem resulted, and although the United States ordered the PUK to withdraw, a PUK administration is still trying to govern the city.

One recent morning, that administration was embodied by a line of 70 garbage trucks, road graders and dump trucks parading through downtown Kirkuk, occasionally honking. Many bore the city seal of Sulaymaniyah, the city in the Kurdish zone where many Kurds from Kirkuk had fled the Arabization campaign.

"We come to serve the people of Kirkuk and keep the city clean," announced Ahmed Ali Hamamin, a municipal employee in Sulaymaniyah. "According to the instructions of [PUK leader Jalal] Talabani, we are to serve the people of Kirkuk whether they are Turkmen, Kurd or Arab."

Hamamin spoke on the city's main street. Graffiti written in Arabic on a wall facing him declared: "Kirkuk without the Turkmen is worth nothing, and the Turkmen without Kirkuk is worth nothing." Behind him, a sign in Turkish read: "Kirkuk Is Ours."

In theory, the nascent administration answers to an 18-member governance committee made up of six Kurds -- three from the PUK and three from the KDP -- six Arabs and six Turkmen. At its first meeting, last Thursday, proceedings were conducted in Arabic and, in a sign of where higher authority lies, translated into English for the U.S. Army officer who ran the meeting.

Brig. Gen. James Parker, the senior commander for U.S. forces in northern Iraq, said the American approach "to all these issues is one of balance. . . . I told them we're not going to order -- and I'll stop it if I find out about it -- any evictions. We're not putting any people out. We're not going to arbitrate property."

"It's not a government," the general said of the transitional structure. "A government will be installed sometime later."

Human Rights Watch, the New York-based human rights organization, criticized the United States and its allies for failing to bring "law and order to Kirkuk and ensure the security of civilians."

"Kirkuk now is a tinderbox," said Hania Mufti, a Human Rights Watch monitor in northern Iraq. "U.S. troops should stop the violence. And PUK leaders should take immediate steps to halt any expulsions of Iraqi Arabs from their homes."

About 90 miles to the north, the Kurds have also taken control of the city of Mosul, where Arabs are the majority of the population. When Iraqi forces abandoned the city five days ago, Kurds were among the most avid looters. In the past two days, 17 people have been killed -- at least seven by U.S. troops -- and 18 wounded in disturbances in the city, according to hospital officials.

The Kurds "say they want to be part of Iraq, but they act like conquerors," said Mahmoud Qusai, a retired Arab ship captain in Mosul. A crowd that had gathered around him murmured, "Let them come, let them come, and they will see."

In the countryside, the PUK is not only deploying armed riflemen, it is taking steps to expel Arabs they say are settlers on the land. Anyone who was transferred from other parts of Iraq by the Hussein government and put on Kurdish land must leave, officials say. "We want it orderly, but the Arab settlers must go," said Gen. Ako Ahmed, self-styled provisional governor of Daqoq district, a county south of Kirkuk that includes Muntasir.

Ahmed denied that the PUK was expelling residents of Muntasir and a half-dozen other rural hamlets in his region. "They will go voluntarily. They have relatives in the south and will live with them," he predicted.

The KDP has actively discouraged the forced expulsion of Arabs. Like the PUK, the KDP says settlers must eventually leave but under an agreement of international organizations and the new Iraqi administration, when it appears. "Kurdish citizens have no right to threaten any Arab citizen or attack any Arab village belonging to indigenous Arab tribes," the KDP's leader, Massoud Barzani, said in a statement.

Barzani's appeal followed several shootouts between Arabs and marauding Kurds. Over the weekend, 12 Kurdish militiamen were killed in an assault on the Arab town of Hawijah, south of Kirkuk. Ezzedin Mohammed, an official of the Red Crescent medical aid society, said he had buried the bodies of 38 people, Arabs and Kurds, involved in fighting in the past two days. "This thing is getting out of hand. We are going from one war to another," he said.

Sadi Qader Muhamad, a Shiite Arab, stands in front of the home in Kirkuk where she lived before it was seized by Kurds. "Kirkuk now is a tinderbox," a human rights observer said of the expulsions in the area.Khader Rashid Rahim, a Kurd, center, stands in front of the home he took from an Iraqi Arab, Qaseem Muhamad Bamed, left, in the city of Kirkuk.