Deadly skirmishes have been on the rise in recent days between U.S. forces and Iran-aligned militias in Syria's oil-rich east, where both have carved out strategic footholds.
Here is a closer look at their rival zones of influence in the desert province of Deir al-Zor, where rocket, mortar and drone attacks have increased - just as negotiations over the revival of a nuclear deal between Iran and the West come to a head.
A PROVINCE DIVIDED
