British men are among a group of international volunteers preparing to fight against Turkish-led forces in north-west Syria, the BBC understands.
They have joined the Kurdish militia, the YPG, to fight the Turkish offensive on the Kurdish-held enclave of Afrin.
Among the volunteers is a 24-year-old British-Chinese fighter from Manchester, known as Huang Lei.
Lei, who originally travelled to Syria in 2015 to battle against IS, told the BBC it was his “duty” to fight.
The YPG has released a video showing an international group of volunteers who previously fought in Syria against so-called Islamic State.
Lei has told the BBC that there are two other Britons with him among the group, although they have chosen to remain anonymous.
In the video, an American says: “We’re all ready to go and fight in Afrin, against the invading force of Turkey.
“We’ve been training for a significant amount of time. We are prepared, and we have been supplied by the YPG to fight against the Turkish terrorists.”
“We were fighting against ISIS in Syria and suddenly we heard that Turkey is attacking Afrin and bombing the city,” he says.
“We want to go there to help people defend the city and protect the people.”
This marks a significant shift in the involvement of international fighters in the Syrian war.
With the IS threat diminished, for some volunteers their mission has changed.