In the course of fighting a counter-offensive in eastern Syria, ISIS has captured at least 10 fighters from the US-backed Kurdish YPG. The fighters were part of the offensive against the ISIS town of Hajin.
The Kurdish forces have been trying to raid Hajin and another nearby town for weeks, with several deployments of reinforcements. ISIS has ambushed fighters as they advanced, and are now trying to turn the tables with their own counter-offensive.
The Syrian Observatory for Human Rights confirmed that 10 fighters have been captured, and are also reporting six others are missing. Whether they were captured or just got separated during the combat is unknown.
Kurdish forces are heavily shelling ISIS positions in the area, and called in backup from US warplanes when the ISIS push began. US planes were apparently not sent, which may be reflective of a difficult targeting environment in the area in recent weeks.
Russia has been warning the USA about this for at least a week.