Kurdish forces are scrambling another 500 fighters into Eastern Syria on Sunday evening to join fighting over ISIS-held territory along the Iraqi border. This is a response to losses inflicted in an ISIS counter-offensive over the weekend.
Over the past week, the Kurds had been making inroads in the town of Hajin, backed by heavy US air support and artillery fire. The ISIS counter-offensive, beginning Saturday, quickly turned the tables and chased them out of the town.
Just north of the Euphrates River near abu Kamal, ISIS controls Hajin and two other nearby towns, along with some adjoining villages. This is their last populated territory under control, and has been under attack by Kurdish forces for months.
The Kurdish forces have made several gains in the area over recent months, but have seen those gains evaporate every time weather takes US air support out of the equation. The large number of ISIS fighters in the area, along with thousands of other ISIS fighters in the deserts of eastern Syria, has meant the Kurds have been unable to overrun them.