U.S. "deterrence" patrols have come under fire several times recently in the northern Syria flashpoint town of Manbij near the Turkish border, a U.S. military spokesman said Thursday.

"There were engagements. They were with small-arms fire that were directed toward our patrols," said Army Col. Ryan Dillon.

"There was more than one," but no U.S. casualties or damage to vehicles or equipment resulted, he said.

The U.S. troops did not return fire, Dillon said. "We did not engage," but "we do reserve the right to defend ourselves. We do not know who is behind these attacks, but we are very clear about our presence there."

U.S. troops have been in Manbij and patrolling other parts of northern Syria since March, when a small contingent of Army Rangers, Stryker fighting vehicles and up-armored Humvees was sent to the town, about 85 miles north of Raqqa.

After a lengthy siege, Manbij was liberated from the Islamic State of Iraq and Syria in August 2016 by the U.S.-supported Kurdish YPG, or People's Protection Units.

The insertion of the Rangers in March this year came as Syrian regime forces backed by Russia approached Manbij from the south, and Turkish forces and their allied Free Syrian Army militia pressed from the east.

Turkey considers the YPG a terrorist group allied to the PKK, or Kurdistan Workers Party, which has been labeled a terrorist organization by the United Nations, Turkey and the U.S.

In late February, Turkish President Recep Tayyip Erdogan warned that Manbij would be the next target in the Turkish military campaign Operation Euphrates Shield, which the Turkish military was conducting inside Syria with Free Syrian Army partners to clear border areas.

To avert a multi-sided battle for Manbij, the Rangers -- flying large U.S. flags from their Strykers and up-armored Humvees -- began conducting what the Pentagon called "overt" patrols in Manbij and on the town's outskirts.

In a March 3 briefing, Navy Capt. Jeff Davis, a Pentagon spokesman, said of the U.S. patrols in Manbij, "We want to have a visible show that we are there" to discourage any moves against the town.

"They're not looking to start a fight with anybody," Davis said of the U.S. troops in Manbij. "They're looking to prevent" any conflict with the Manbij Military Council, the mostly Syrian-Arab group that has policed Manbij since the ouster of ISIS.

With U.S. troops in Manbij, there was no need for Turkish, Russian or Syrian regime forces to move on the city, Davis said.

"This is a new effort. This is the first time we've had to do something like this, which is to ensure that we are out there as a visible symbol that the enemy is cleared out of Manbij," Davis said. "There is not a need for others to advance on it in attempts to 'liberate' it."

In a briefing from Baghdad to the Pentagon on Thursday, Dillon, a spokesman for Combined Joint Task Force-Operation Inherent Resolve, said the incidents in Manbij are having no effect on the ongoing siege of ISIS-held Raqqa to the south.

Dillon said the U.S.-backed Syrian Democratic Forces, a mix of Syrian-Arab and YPG troops, have control of more than 50 percent of Raqqa but are running up against tougher resistance, mostly from ISIS' improvised explosive devices.

"There's no question they have hit fiercer resistance," he said, but the SDF is pressing the fight and has not lost any ground.

-- Richard Sisk can be reached at Richard.Sisk@Military.com.