The spokesman said they were sharing the message after consulting with Mr Aslin’s family. “Hope for a prisoner exchange,” he said. Mr Aslin also fought in Syria with the Kurdish YPG militia. River O’Mahoney Hagg, who was a combat doctor there, shared a message on Instagram that apparently came from a source in Ukraine. “I beg you for your prayers,” the message said, adding that Mr Aslin’s unit “has no choice but to surrender.”