MAKHMUR, IRAQ // The sand berms and trenches that snake across northern Iraq stretch toward Syria, some accompanied by newly paved roads lit by street lamps and sprawling checkpoints decked with Kurdish flags.

The fighters here insist it isn’t the border of a newly independent state – but in the chaos of Iraq that could change.

Construction began in 2014, when this marked the front line between US-backed Kurdish peshmerga forces and ISIL, which had swept across northern Iraq that summer, routing the army and threatening the Kurdish autonomous region.

Since then, a more permanent boundary has taken shape as Kurdish aspirations for outright independence have grown. The frontier could mark the faultline of a new conflict in Iraq once the extremists are defeated. A similar process is underway in Syria, where Syrian Kurdish forces have seized large areas of land from ISIL.

“It was our front line, now it’s our border, and we will stay forever,” said peshmerga commander and business magnate Sirwan Barzani. He is among a growing number of Kurdish leaders, including his uncle, the Kurdish region’s President Massoud Barzani, who say that lands taken from ISIL will remain in Kurdish hands.

The Kurds have been at loggerheads with the Baghdad government over the so-called disputed territories – lands stretching across northern and eastern Iraq – since the 2003 US-led invasion. Article 140 of the Iraqi constitution says their fate should be decided by a referendum, but such a vote has yet to be held, and as the Iraqi army collapsed in 2014, the Kurds moved in.

They took control of the long-disputed northern city of Kirkuk that summer, ostensibly to protect it from ISIL. Since then, with the aid of US-led air strikes, the Kurds have taken territory equivalent to 50 per cent of their recognised autonomous region.

“After the defeat of ISIL, Sunnis will dispute the Kurdish claims, the Shiites in Baghdad will dispute both the Sunni claims and the Kurdish claims, and the possibility of conflict there is real,” said Anwar Anaid, dean of social sciences at the University of Kurdistan Hewler.

“What happens on the ground depends on the circumstances. There is a real Kurdish wish to go for independence.”

Peshmerga commander Aref Taymour said that once ISIL is driven from the northern city of Mosul, the Kurds will negotiate a new border with Baghdad. But he added that “lands that have been liberated by blood, we have no intention to give them back to the federal government”.

Another Kurdish official, Dishad Mawlod, was even more direct, describing the fortifications as the “future borders of Kurdistan”.

“We’re not violating any international laws, nor are we occupying anyone’s land,” he said.

Mr Barzani, the regional president’s nephew, said the Kurds no longer trust the Iraqi army to defend the country, after it lost nearly a third of it to ISIL two and a half years ago.

“Of course there will be another Daesh,” he said.

“None of the internal Iraqi issues have been resolved,” he added, saying the Kurds “will be ready”.

In the meantime, he hopes for talks on independence as early as next year.

“It’s a bad marriage, let’s get a divorce,” he said.

The Baghdad government is staunchly opposed to Kurdish independence, and prime minister Haider Al Abadi said he expects the Kurds to abide by an agreement that they withdraw from areas captured since the start of the Mosul operation in October.

“Some Kurdish politicians are saying otherwise. But they are not responsible people and they are not controlling events on the ground,” Mr Al Abadi said last week.

The two sides have set the dispute aside as they work together to drive ISIL from Mosul, Iraq’s second largest city, but the construction along the frontier is continuing. On one road south of Mosul, peshmerga fighters were building cinderblock stairways leading to offices in trailers, as guard posts were being set up further along the line.

Aware of the sensitivities, Iraqi soldiers and Kurdish fighters stationed along the frontier are reluctant to speak about the matter.

“You can’t take pictures, and whatever you do, don’t call this a border!” a peshmerga fighter said as he came sauntering out of a checkpoint complex along the frontier. He refused to give his name.

At a nearby army position, Iraqi soldier Hussein Jassem acknowledged that “there is a border between us and the peshmerga” but declined to comment further.

* Associated Press