Tanks with soldiers holding the Turkish and Iraqi flags rolled on a field lifting up dust, as the two countries' militaries conducted joint exercises on Turkey's border with Iraq's semi-autonomous Kurdish region.

Some 30 Iraqi troops have arrived in the border region to join ongoing Turkish military manoeuvres that were launched last week in a symbolic warning to Iraqi Kurds who held a landmark referendum on independence Monday.

Kurdish leadership billed the vote as an exercise in self-determination, but it's viewed as a hostile act by Iraq's central government. Neighbouring Turkey even threatened a military response.

To Baghdad, the vote threatens a redrawing of Iraq's borders, taking a sizable part of the country's oil wealth with it. For Turkey and Iran, leaders feared the move would embolden their own Kurdish populations.

The vote — likely to be a resounding Yes when official results are revealed later this week — is not binding and will not immediately bring independence to the autonomous region. Nevertheless, it has raised tensions and fears of instability in Iraq and beyond.

Just hours after polls closed Monday night across the Kurdish region of northern Iraq, the Defence Ministry announced the launch of "large-scale" joint military exercises with Turkey.

Turkey threatens military intervention

Earlier in the day, President Recep Tayyip Erdogan of Turkey threatened the Kurdish region with military intervention. Iran, which also opposed the vote, held military exercises along their border Sunday.

The Iraqi Kurdish push for independence has been made even more combustible because Kurdish forces captured extensive territory in fighting against the Islamic State in Iraq and Syria group in the past year. Those areas run from northwestern Iraq to the Iranian border on the east — including the oil-rich city of Kirkuk. Baghdad claims those territories, but the Kurds say they are part of their zone and some residents there are participating in the referendum.

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Turkish President Recep Tayyip Erdogan is threatening military intervention in Iraq in response to the Iraqi Kurdish region's referendum on independence. (The Associated Press)

An escalation in rhetoric within Iraq set the stage for increased tensions as Iraqi Kurds lined up to vote.

The Kurdish region's president, Masoud Barzani, and Iraqi Prime Minister Haider al-Abadi both threatened to use force ahead of Monday's vote.

Iran's parliament will hold a closed-door meeting Wednesday on the referendum. During the meeting, lawmakers will be briefed about Monday's vote.

The meeting comes as parliament speaker Ali Larijani on Tuesday criticized the vote. State television quoted him as saying there are "elements" … "making provocations" in Iraq's Kurdish region.

Thousands of Iranian Kurds demonstrated into the early morning Tuesday to celebrate the vote.

The Arab League is calling on Iraqis to renounce their differences and open comprehensive dialogue to avoid clashes.

Ahmed Aboul-Gheit, chief of the Cairo-based pan-Arab organization, said in a statement: "It is still possible to contain the repercussions of this step if all concerned parties exercise wisdom and responsibility and conduct themselves inside the parameters of the Iraqi state."

The interests of Iraq, he added, "will be best served in the framework of a unified, federal and democratic Iraq."

'Ready to pay any price'

Barzani softened his tone before he voted. He told a news conference Sunday that he believed the vote would be peaceful but acknowledged the path to independence would be "risky."

"We are ready to pay any price for our independence," he said.

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Iraq's Kurds defied widespread opposition to vote in the historic independence referendum, sparking fresh tensions with Baghdad, threats from Turkey and fears of unrest. (AFP/Getty Images)

Al-Abadi had said on the eve of the referendum that the vote "threatens Iraq" and "is a danger to the region."

"We will take measures to safeguard the nation's unity and protect all Iraqis," he warned in a televised address from Baghdad.

U.S., UN oppose vote

The United States and United Nations both opposed the vote, describing it as a unilateral and potentially destabilizing move.

U.S. State Department spokesperson Heather Nauert said the U.S. wouldn't alter its "historic relationship" with Iraqi Kurds but the referendum would increase hardships for the Kurdish region of Iraq. She said ISIS and other extremists are hoping to "exploit instability and discord."

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Some five million Kurds took to the polls to vote in the referendum Monday. (Chris McGrath/Getty Images)

Statements from UN Secretary General Antonio Guterres expressed regret that the vote was held and said issues between Iraq's federal government and Kurdish region should be resolved through dialogue.

The promise of an independent state has long been at the centre of Iraqi Kurdish politics. When colonial powers drew the map of the Middle East after the First World War, the Kurds were divided among Turkey, Iran, Syria and Iraq.

'I feel we'll be free'

That dream was evident among some of the voters in the disputed city of Kirkuk.

"I feel so great and happy. I feel we'll be free," said Kurdish resident Suad Pirot after voting. "Nobody will rule us. We will be independent."

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The promise of an independent state has long been at the centre of Iraqi Kurdish politics. (Khalid Mohammed/Associated Press)

The oil-rich city has large Kurdish, Arab, Turkmen and Christian communities, and it has seen some low-level clashes in the days leading up to the vote. A curfew was imposed Monday evening for fear of more violence.

Baghdad residents strongly criticized the referendum, saying it would raise sectarian tensions and create an "Israel in Iraq."

A 'black day'

"This is a division of Iraq," said journalist Raad Mohammad. Another Baghdad resident, Ali al-Rubayah, described the vote as a "black day in the history of the Kurds."

Lawyer Tariq al-Zubaydi said the referendum was inappropriate amid the "ongoing threat of terrorism and Islamic State" militants.

"The country is going through a difficult period. This requires a coming together of our efforts, he said. "A unified country is better for all."

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Two Iraqi Kurds show their inked fingers after casting a vote. (Khalid Mohammed/Associated Press)

Speaking in Istanbul, Erdogan said Turkey doesn't recognize the referendum and declared its results would be "null and void."

Erdogan also suggested Turkey could halt the flow of oil from a pipeline from northern Iraq, a lifeline for the land-locked Kurdish region battling a severe economic crisis.

Turkey has urged the international community — and especially regional countries — not to recognize the vote and urged Iraq Kurdish leaders to abandon "utopic goals," accusing them of endangering peace and stability for Iraq and the whole region.

"We could arrive suddenly one night," Erdogan said, pointing to Turkish military exercises underway along Turkey's border with the Iraqi Kurdish region.

"Our military is not [there] for nothing," he added.