MULA ABDULA, Iraq >> Among rolling wheat fields with machine-gun fire rattling in the distance, Kurdish fighters patrol the new frontier of their autonomous region of northern Iraq, dozens of miles from their official border. In front of them are Islamic militants, behind them is the Kurds’ newly captured prize, stretches of oil-rich territory.

In Iraq’s chaos, the Kurds are emerging as significant winners — and their victories are fueling sentiment among their population to declare outright independence.

As Sunni insurgents swept over a large chunk of northern Iraq and barreled toward Baghdad the past two weeks, Kurdish fighters known as peshmerga seized territory of their own, effectively expanding the Kurdish-run region into areas it has long claimed. Most notably, they grabbed the oil center of Kirkuk. And in contrast to the Shiite-led government in Baghdad, which is in turmoil, the Kurds are growing more confident, vowing to increase oil sales independent of the central government.

The gains have also brought the Kurds challenges barely imaginable just days ago. They must defend a new, 620-mile (1,000 kilometer) frontier against Sunni insurgents, led by an al-Qaida breakaway group, the Islamic State of Iraq and the Levant. Some 300,000 Iraqis who fled the insurgent advance have flooded into Kurdish areas, an extra burden to an already cash-strapped autonomy government.

And the Kurds risk a backlash. In Kirkuk, Sunni Arabs and ethnic Turkmens — who have long opposed Kurdish claims over the city — threaten a revolt if the Kurds don’t share administration of the city and any oil revenues.

Still, the sense of exuberance is palpable among Kurds, who make up 20 percent of Iraq’s mostly Arab population.

“Now that the peshmerga took back our disputed areas, we should have our own country. We deserve it,” said Khaled Ismail in the Kurdish area of Khazer.

The 19-year-old student wants independence so Kurdistan can sell its own oil and have the status statehood brings like a passport, representation internationally — and a national soccer team. “If we had a Kurdish team in the World Cup, it would be great,” he said.

Another man pointed to the strength of the peshmerga, who fought back against the insurgents in contrast to the troops of Shiite Prime Minister Nouri al-Maliki’s government, who collapsed.

“The peshmerga and al-Maliki’s army are as different as the ground and the sky,” said 59-year-old Ahmed Omar, wearing traditional Kurdish baggy pants. He also wants statehood. “We don’t want other people to interfere in our affairs.”

However, declaring independence — and formally fragmenting Iraq — is not easy. The United States and neighboring Turkey oppose Kurdish independence. And the Kurds can expect constant clashes not just with insurgents but with Iraqi forces as well if they unilaterally break away and claim the areas they grabbed, said Kurdish analyst Hiwa Osman. “If the Kurds want true independence, (there) has to be a treaty,” he said.

Given that resistance, the Kurdish government is pressing for even greater powers of autonomy but not full independence.

The Kurds’ territorial grab is substantial. The recognized Kurdish autonomous region — defined as three northern provinces — effectively expanded by 40 percent, estimated Gareth Stansfield, an expert on Kurdish affairs.

The peshmerga moved into territory all along the edges of their region, from near the Rabia border crossing into Syria in the northwest to the city of Jalula in the southeast near the Iranian border.

The Kurds say the move was to protect those areas when the military fled the insurgents’ advance after the Islamic State captured the northern city of Mosul on June 6.

But many of these areas have large Kurdish communities that the Kurds have long demanded be incorporated into their zone — making them unlikely to give them up.

This week, the peshmerga patrolled the frontline separating them from Sunni insurgents, along wheat fields in an area known as Mula Abdula. The area is more than 30 miles (50 kilometers) from the official Kurdish zone’s borders. The area was littered with bullet casings, and gunfire and the occasional thud of a tank shell could be heard from fighting further down the road.

Some 15 miles behind them, in Kurdish hands, was Kirkuk and surrounding oil-rich lands.

“It’s by far the biggest field in the north, and now the Kurds sit on top of it,” Stansfield said.

The Kurdish autonomous zone has its own oil resources, currently producing about 220,000 barrels a day, and it has long argued with Baghdad over sharing revenues from that oil. The Kurdish government in May sold oil independently of the central government for the first time– around 1.05 million barrels, shipped out by their own pipeline to Turkey. In retaliation, Baghdad stopped giving the Kurds the proportion of the central budget they are entitled to receive.

Safeen Dizayee, the Kurdish regional government spokesman, said the Kurds intend to increase independent oil sales, aiming for 400,000 barrels a day.

“The more we can produce, the more we will sell,” he said.

He did not say whether they would take the more provocative step of selling oil from Kirkuk. Stansfield said it wouldn’t be difficult to pump Kirkuk’s oil to the nearby capital of the Kurdish zone, Irbil. If that happens, “the geography of the oil industry could change quite quickly.”

Such an explosive move would signal the Kurds’ intention to keep Kirkuk, where they have a large population. It would infuriate not only Baghdad but other ethnic groups — Arabs and Turkmen — who also live in Kirkuk and claim it as their own.

On Kirkuk’s edge, a leading Arab tribal elder said heavily-armed men were waiting to see if Kurds would share administration of the city and its oil.

If not, “then we must have an uprising against them,” said Sheik Abdul-Rahman al-Awaidi. “Nobody is stupid enough to give up Kirkuk.”

A leading Turkmen official said his community is also arming its men, partly to defend against militants but also in case Kurds won’t share Kirkuk. “Turkmens need to defend themselves,” said Arshad al-Salihi.

In a market on a Kirkuk street, men busily bought weapons looted from abandoned army bases. Nearby, Kurdish police patrolled in uniforms emblazoned with the colors of the Kurdish flag — red, white and green with the emblem of a golden sun.

Further north, Kurdish officials are dealing with with 300,000 Iraqis who fled there the past two weeks — adding to 260,000 Syrian refugees and Iraqis who fled earlier fighting already in their areas.

“Kurdistan’s doors are staying open and we are offering all the help that we can,” said Falah Bakir, the Kurds’ top foreign policy official.

Stansfield said the Kurds could cite the need for funds to take care of refugees to convince the West to consent to it selling oil independently of Baghdad.

And while the Kurdish administration says it does not seek to break from Iraq, it clearly feels that as the rest of the country falls apart, it wants powers like selling oil that would bring it to virtual statehood.

“We are not the ones who should be accused of the disintegration of Iraq,” said spokesman Dizayee. “Others are helping to take Iraq in that direction.”