US Defence Secretary Jim Mattis said on Friday that tensions between Kurdish and Iraqi forces in and around Kirkuk had the full attention of the United States, which was working to ensure it does not escalate.
Kurdish authorities said they have sent thousands more troops to Kirkuk to confront "threats" of Iraqi military attack, but also pulled back defense lines around the disputed oil-producing area slightly to ease tensions.
Mattis told reporters:
We have got to work on this, the secretary of state has the lead, but my forces are integrated among these forces and they are working too, to make certain we keep any potential for conflict off the table
The Baghdad central government has taken a series of steps to isolate the autonomous Kurdish region since its overwhelming vote for independence in a September 25 referendum, including banning international flights from going there.
Mattis said while he was aware of troop movements, he had not heard of any fighting and called on both sides to focus on fighting Daesh militants.
"We can't turn on each other right now. We don't want this to go to a shooting situation," Mattis added.
Read: Why the Kurdish referendum means the end of Iraq
Kirkuk, a city of more than 1 million people, lies just outside Kurdish territory, but Peshmerga forces deployed there in 2014 when Iraqi security forces collapsed in the face of a Daesh onslaught. The Peshmerga deployment prevented Kirkuk's oil fields from falling into militant hands.
As the territory controlled by Daesh has shrunk, ethnic and sectarian fractures that have plagued Iraq for more than a decade have once again started to resurface.
The group's last territory in Iraq is now a stretch skirting the western border with Syria following the fall of the town of Hawija and surrounding areas on October 5 in an offensive by US-backed Iraqi forces.
Mattis said the differences would have to be worked out politically and not on the battlefield.
"These are issues that are longstanding in some cases…We're going to have to recalibrate and move these back to a way (where) we solve them politically and work them out with compromised solutions," he said.
Read: Armed forces of Iran and Iraq to hold joint border drills