A British national who traveled to Syria to fight against ISIS says he and two dozen other foreign fighters are now battling Turkish forces over territory in the country.
One of the foreign fighters, 24-year-old British national Huang Lei, told CNN that about 25 people from the West were currently in northern Syria's Afrin region helping the People's Protection Units (YPG) hold on to land, as Ankara tries to seize it from the Kurdish group's hands.
Another six foreign fighters, including one with an American-sounding accent, were seen in a YPG video posted on social media, preparing to travel to Afrin to fight.
An official from the Syrian Democratic Forces, an alliance in which the YPG fights, said that US, British and German citizens were among the "tens" of fighters in Afrin, Reuters reported.
CNN exchanged messages with Lei via his Weibo social media account on Wednesday. CNN could not independently verify his account.
Lei, from the northern English city of Manchester, claimed he was fighting ISIS in another part of Syria just days ago, he told CNN from Afrin.
"I came here to defend the people of Rojava from terrorism," he said, referring to an expansive northern Syrian region.
"It makes no difference if the aggressors are (ISIS) or the Turkish military. In Afrin, Turkey knowingly targets civilian buildings such as hospitals."
With ISIS on the brink of eradication in Syria, foreign fighters are left with the choice or returning home or continuing to support the militia groups they joined.
Before joining the YPG, Lei said he was a-student in international politics at the University of Manchester. He left the UK in 2015 and said that, eventually, he wanted to go back to his home country.
"This is why I came here. Keep the evil away from my home country and fight against the terrorists, " he said.
It was not clear whether Lei had stayed in Syria for the entire period since 2015.
The Syrian civil war that has raged for nearly seven years has attracted thousands of foreign fighters, some who joined jihadist groups, and others who teamed up with the militia fighting against them.
But the new focus on Turkish forces marks a major shift in the role of foreign fighters in the conflict.
Ankara, which has long fought Kurdish unrest in southeastern Turkey, is determined to prevent the establishment of a Kurdish state at Turkey's border with Syria. It has used military force for decades in the country's southeast, and has also carried out strikes over the Syrian border.
YPG: Afrin operation a 'terrorist project'
In the YPG video, six foreign fighters holding weapons line up in front of the camera to announce their intention to fight Turkey in Afrin. Four of them cover their faces.
"We've been training for a significant amount of time in tactics that work against any force," said one of the fighters, who showed his face and spoke with what seemed to be an American accent.
"It wasn't really something that was unexpected," he said later, calling the Turkish government an "invading force."
Mustafa Bali, a spokesman for the Syrian Democratic Forces -- of which the YPG is a part -- told CNN that the six fighters in the video were not new recruits.
"We have a group of international fighters that joined the YPG in its fight against ISIS in Kobane and these fighters are present with us in all of our revolutionary campaigns against ISIS, in every place," he said.
"Now these fighters consider that the war on Afrin is part of the terrorist project, and for that reason they have taken the decision to join the resistance in Afrin. Of course, we do not force upon them the choice of leaving or remaining."
A coordinator for the YPG's foreign relations unit told CNN in December that, since 2014, approximately 300 foreign volunteers had joined its military ranks and another 500 foreigners had volunteered in a civilian capacity. Not all those fighters are still with the group.
Turkey launched its operation in Afrin four days ago, targeting the YPG, which Ankara says is a terrorist organization and a mere extension of the Kurdistan Workers' Party (PKK). Turkey, the US and EU all consider the PKK a terrorist organization.
But Washington backs and arms the YPG in other parts of the country as a leading force in the fight against ISIS.
CNN has not been able to independently verify a casualty toll on either side.
CNN reporters on the Turkish-Syrian border have heard artillery shelling for the past two days, while a journalist who lives in Afrin said Turkish warplanes carried out five airstrikes in the morning. Despite the bombardment, he said that life in Afrin was largely business as usual. Afrin residents are still sending their children to school and are still visiting marketplaces.
The journalist says his daughter points to the Turkish warplanes and laughs.
"The people here have no choice but resistance," he said.
"We've gotten past the horror and the fear that the Turks have tried to instill in us."