Travel through northern Iraq and you’ll notice something strange. Most of the flags aren’t Iraqi ones; they’re the red, white, green, and yellow flag of the Kurds, who have long sought to carve out a new nation of their own there.

With the eyes of the world focused on North Korea, the Kurds have just taken a large — and very dangerous — step in that direction by overwhelmingly approving a referendum on formally declaring independence from the Iraqi central government in Baghdad. Qubad Talabani, deputy prime minister of the Kurdistan Regional Government (KRG), called it a “historical day” for Kurds.

The referendum isn’t binding, and there’s no sign that the US-backed government in Baghdad has any intention whatsoever of acting on it. In a televised speech on Sunday, just one day before the referendum vote, Iraqi Prime Minister Haider al-Abadi called the vote “unconstitutional” and declared that Baghdad “will not recognize its outcome.”

Still, the mere act of holding the vote risks a new rupture between the Kurds and the Iraqi government — one with a real risk of actual fighting between the two sides.

On September 18, seven days before the referendum, Iraq’s supreme court ordered the Kurds not to hold the vote. But Kurdish leaders ignored the order, holding the vote not just in Kurdish areas but also in the “disputed territories” that have significant numbers of both Arabs and Kurds. That means the Kurdish government in northern Iraq is making a bold play for power in areas still bound to Baghdad.

Iraq’s neighbors are not pleased either. Iran has built close ties to Baghdad, and worries that an independent Kurdistan would weaken Iraq and potentially encourage separatist movements among its own Kurdish minority of about 8 million Iranians. An independent Kurdistan could also become a military hub for Western forces on Iran’s doorstep.

Turkey, which has waged a bloody decades-long war against its own Kurdish separatists, has called the inclusion of the disputed territories a “grave mistake.” This spells trouble for the Kurdish government in Erbil: Turkey is the only gateway for the export of Kurdish oil to international markets. Turkish President Recep Tayyip Erdogan has threatened to choke off Kurdistan’s lifeline.

In a joint statement issued last week, Turkey, Iran, and Iraq warned that the referendum could distract from the fight against ISIS and jeopardize recent advances. They say they’ve agreed to consider countermeasures against Kurdistan (though what countermeasures, exactly, remains unclear). The Iraqi constitution does not have a mechanism for secession; independence cannot happen without a decision by the Iraqi parliament, which would definitely reject the Kurdish push.

All of that means it’s unclear what the referendum will have achieved, beyond giving Kurdish leaders more of a mandate to pursue secession talks, no matter how unlikely those talks are to succeed.

“It will be like Brexit,” says Najmaldin Karim, governor of the oil-rich Iraqi city of Kirkuk. He meant that optimistically, but it’s not necessarily a comparison Kurds should cheer given the bitter, unproductive status of Brexit negotiations.

Kirkuk will be the battleground

“Iraq has always failed as a state,” says Karim, a Kurd who returned to his hometown of Kirkuk in 2009, after 30 years in the US. Karim wants Kirkuk, one of the country’s disputed territories, to be part of an independent Kurdistan.

Kurds have a historical claim to Kirkuk. Saddam Hussein forcibly displaced them during his “Arabization” campaign in the 1980s. Since 2003, they have moved back to reclaim it. Jalal Talabani, the founder of the Patriotic Union of Kurdistan (PUK), one of the main Kurdish political parties, has called Kirkuk the “Jerusalem of the Kurds.”

And though the province is ethnically mixed, it has been under de facto Kurdish control since June 2014, when Kurdish peshmerga forces defended it from ISIS, filling the vacuum left by the fleeing Iraqi military. Now the Kurdish flag flies alongside the Iraqi federal one in the city of Kirkuk (which shares the same name as the province). Earlier this summer, Karim defied orders from an Iraqi court to take it down: “The Kurdistan flag will fly high,” he insisted.

Kirkuk is a flashpoint largely because of its massive oil wealth. Nine billion barrels of oil reserves lie just outside the city — 6 percent of the world’s total and 40 percent of Iraq’s. These reserves are capable of producing more than 1 million barrels a day, though as of last year they have been pumping at only half capacity, according to data from the Iraqi oil ministry.

Until recently, Baghdad produced and sold all of Kirkuk’s oil. But after ISIS sabotaged Baghdad’s pipeline and peshmerga forces streamed in, Baghdad lost control. Kurds now control three of the five oil fields. A deal reached in August 2016 ensured that both Kurdish and Iraqi governments get a share of the oil proceeds, but Baghdad wants its oil fields back. Yet Kurdistan needs oil revenue from Kirkuk to pay even a fraction of the costs of running a quasi-independent Kurdish state, says Luay Al-Khatteeb, director of the Iraq Energy Institute, a London-based think tank.

Kirkuk’s value is also symbolic. It was the first place Iraq discovered oil in 1927. A lot of Iraqis have grown up knowing Kirkuk as one of the country’s great cities, says Michael Knights, a fellow at the Washington Institute for Near East Policy. If Kirkuk goes, it feels like Iraq is breaking up.

Krexit?

The last reliable Iraqi census in 1957 put the population of Kirkuk at around 50 percent Kurds, 30 percent Arabs, and 20 percent Turkmen. Now it has also taken in more than 500,000 Arabs displaced by the fight against ISIS. Arabs and Turkmen called for a boycott of the vote.

Nevertheless, the electoral commission announced on Wednesday that the outcome was a resounding “yes.” Of the 3.3 million Kurds and non-Kurds who cast ballots, 92 percent voted for secession. The Iraqi parliament has responded by asking the prime minister to deploy troops to Kirkuk and the surrounding area.

Baghdad’s only way to regain control of Kirkuk is through negotiations or fighting, says Bilal Wahab, a fellow at the Washington Institute for Near East Policy. The peshmerga and Shia militias have cooperated in the fight against ISIS. As their common enemy nears defeat, they may turn on each other.

Shia militias, which were funded by the Iraqi government to fight ISIS, have threatened to retake the city. They are technically part of the Iraqi security apparatus, and any attack could easily escalate into civil war unless Baghdad disowns them, says Wahab. Karim has summoned peshmerga reinforcements in response.

Western forces, including the United States and the United Nations, urged the Kurdish government to call off the vote, citing the need for a peaceful reconstruction of the territories regained from ISIS and the safe return of refugees. The US has offered Masoud Barzani, the Kurds’ president, and Haider al-Abadi, Iraq’s prime minister, a room at the American Embassy in Baghdad to negotiate a deal. Oil could help lubricate relations. A revenue-sharing deal with Baghdad is the only way Kirkuk won’t blow up, says Wahab.

Kurdish leaders still say they will do whatever it takes for independence. Vincent Stewart, director of the Defense Intelligence Agency, testified this summer that Kurdish independence is a matter of “not if but when.” Karim says of the 30 million Kurds dispersed across the Middle East: “We’re the largest ethnic group in the world that doesn’t have a recognized nation state.”

Elizabeth Winkler is a journalist based in Washington, DC. Find her on Twitter @ElizWinkler.