New neutral arbitrators will be needed at centres set up to prevent disputes between Kurdish and Arab forces after the year-end departure of US troops from Iraq.
All US troops must leave by December 31 unless Baghdad and Washington reach an accord to allow a training mission to stay on.
Without an extension, the three centres which mediate disputes in ethnically mixed areas patrolled by combined Kurdish and Arab Iraqi units will need to find a new way to fill the US role.
Brigadier General Jim Pasquarette, deputy commander of US forces in north Iraq, said last month he would like an agreement on the future of the centres to be implemented by the end of next month.
Kurdish authorities want to incorporate large swathes of disputed territory along the de facto border of Iraqi Kurdistan in the north into their autonomous region, a scenario rejected by the central government in Baghdad.
US security officials have long pointed to the unresolved boundary issue as one of the biggest long-term threats to Iraqi stability. The International Crisis Group in 2009 dubbed it the "trigger line."
"The biggest challenge we face... is who is in charge if the US is not here," said Lieutenant Colonel Ted Stuart, who has since October 2010 headed the Nineveh Combined Coordination Centre (NCCC), south of the city of Mosul.
The NCCC includes representatives from the Kurdish Regional Guards Brigade, or peshmerga, the Iraqi army, Nineveh provincial police, and the US military, with the other two centres in Diyala and Kirkuk provinces formed on similar lines.
The joint system was proposed in 2009 and implemented early last year, setting up 22 checkpoints across Nineveh, Diyala and Kirkuk in addition to the three centres.
The checkpoints are manned by Iraqi soldiers and Kurdish peshmerga fighters, as well as Iraqi policemen at times. US forces were also posted at the checkpoints until the beginning of August.
"We represent the party that everybody else can agree on as the one that they will agree to follow," said Stuart.
"So the question then becomes, when the Americans are gone, who does the centre report to, first of all, and second of all, who is in charge within the centre?"
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The first question, he said, will probably be resolved by the formation of a regional combined coordination centre, to which the three provincial centres would report.
But "as far as the question of who's in charge internally here, we're actually still fighting our way through that one."
Stuart said he believed the likely result would be a rotational leadership or a power-sharing system.
"That issue is really the key. If we can resolve that to everybody's satisfaction, I think the rest of the work will continue as it has," the official said.
Major Ali Jassem al-Tamimi, an Iraqi army representative to the NCCC, was confident the centres would continue to function after the US withdrawal, but conceded that disputes may arise.
"We expect that after the US withdrawal, we will work in the same way and... the same effort will continue, but there might be some small conflicts between one side and another," Tamimi said.
Captain Massud Hussein, representing the peshmerga, agreed with Tamimi, but added that the situation "will be improved for the better if they (the Americans) stay."
"In the beginning when the centre was established, some problems happened between us... between the Kurdistan Regional Guards, the police and the army," said Colonel Ahmed al-Jubburi, who represents the Nineveh police.
But "with the presence of the US forces we managed to get over these problems and now we have good relations," he said. "The role of the US forces was very clear... and they were able to solve many problems."
Asked if he was concerned about disputes arising after the US withdrawal, Stuart responded: "Certainly."
The NCCC, he said, has to approve military operations in the ethnically-mixed areas patrolled by the local police, Kurdish forces and the Iraqi army, which are known as Combined Security Areas (CSAs).
"The intent of that is to give transparency to what each side is doing and prevent routine actions from being misunderstood," he said.
"The second part of our mission here is when problems do inevitably happen, we assist with resolving them and preventing them from growing into bigger issues," he said.
Stuart said informal talks have been held at the NCCC on the post-US future of the centre, and that a draft memorandum of agreement is in the works. But no final accord has so far been agreed.