A main border crossing between Syria and Iraq is now being contested, on the Syrian side, by Assad's troops and the anti-Assad rebels. They are fighting for control of Abu Kamal, just up the Euphrates from Al Qaim, Iraq. The fighting has effectively closed the border to Syrian refugees seeking to enter Iraq, leaving some 100 families stranded in the desert with no water, food, or shelter. Thousands have crossed during the year, necessitating large refugee camps in Al Qaim.
The rebels hold the town of Abu Kamal, but the Syrian army controls the airfield and military base outside the town. It's an active battle now for this valuable crossing. The rebels would love to hold it as a supply route. It's a large headache for Iraq and now that cross-border shelling has hit Al-Qaim it becomes a serious threat to the region.
Back in 2005 this border crossing saw military equipment entering Iraq to arm al qaeda and other forces labeled 'insurgents' by the U.S. The U.S. attempted to close the border to prevent the flow of weapons. They even invaded Syria around Abu Kamal in a failed attempt to drive anti-U.S. forces from massing across the border. The U.S. army was forced to withdraw, suffering large casualties.
Now the flow of arms is in the other direction as foreign-to-Syria elements seeks to arm the anti-Assad forces. And flow of innocent civilians is dammed/damned at the border.