A U.S. patrol came under fire in the Syrian region of Manbij, allegedly from Turkey’s local proxy forces.

American officials with Operation Inherent Resolve confirmed to Military Times that coalition forces exchanged fire with an unknown armed group on Oct. 15 near Manbij — a region in northern Syria that has stoked tension between the U.S. and Turkey, both NATO allies, over the past year.

“Troops were on a patrol with Manbij Civil Council and received gunfire from an unknown source," Army Col. Sean Ryan, spokesman for the Inherent Resolve coalition to defeat the Islamic State, told Military Times.

"It was over quickly and a reminder to stay vigilant,” he added.

Ryan said the coalition patrols in Manbij do not often receive fire. He also did not confirm whether those firing at the Americans were Turkey’s proxy forces.

“Manbij has been relatively safe but it is still Syria, and a lot of malign actors are looking to cause trouble,” he said.

The Syrian Kurdish journalist Hosheng Hesen posted a video of the skirmish on his Twitter account. He wrote a caption stating that the video shows a clash between U.S. troops and armed rebel factions sponsored by Turkey.

Earlier this year, Inherent Resolve confirmed to Military Times that coalition forces have received fire from suspected Turkish-supported groups sporadically over the time they have been patrolling near Manbij.

Regardless, Ryan said he didn’t expect this incident to derail efforts to cool tensions between Turkey and the U.S.

Manbij has been a flash point in relations between the U.S. and Turkey, with coalition troops caught in the middle of a geopolitical rivalry between the two NATO allies.

Inherent Resolve coalition forces, including U.S. and French troops, have been patrolling Manbij over the past year, amid Turkish demands for the withdrawal of the People’s Protection Units, or YPG, a Kurdish militia that dominates the U.S.-backed Syrian Democratic Forces and helped expel ISIS from the area in 2016.

Turkey views YPG fighters as terrorists because of their links to the ongoing Kurdish insurgency in southeastern Turkey.

In order to defuse tensions with Turkey, U.S. officials reached an agreement on a Manbij roadmap to determine how the area would be governed that involves the departure of YPG fighters.

Since June, troops from the two countries have been conducting “coordinated independent patrols” along the demarcation line north of Manbij. And training for actual joint patrols between U.S. and Turkish troops is also underway, Pentagon officials told reporters this month.

Turkey’s proxy force — ethnically Syrian Arab and Syrian Turkmen rebels who are known as the Turkish-backed Free Syrian Army, or TFSA — have been used in the past by the Turkish military during operations in northern Syria, such as the battle to uproot Kurdish fighters from Afrin.

TFSA rebels have also threatened to retake Manbij.

However, Ryan confirmed U.S. troops would not be conducting joint patrols with TFSA fighters. Instead, they will directly work with Turkish uniformed soldiers.

“The patrols will be with the Turkish Army and should start soon,” Ryan said.

Despite the roadmap, Turkish President Recep Tayyip Erdogan has continued to accuse the U.S. of not pushing the YPG hard enough to depart.

“America has not kept up with the roadmap and schedule for Manbij,” Erdogan told Turkish media in September. “The [YPG] has not left the region.”