Iraq is struggling to tighten control of its border with Syria, alarmed by a resurgent al Qaeda force that seeks to build an Islamic state across a frontier drawn in colonial times.

The Baghdad government has deployed troops and new U.S.- and Russian-made weaponry to try and cut the militants’ cross-border supply lines, hoping that can kill off the threat. But as U.S. forces found before them, it is a near-impossible task.

The Syrian civil war that has inflamed sectarian tensions across the region, and a desolate geography favoring smugglers and guerrillas are just two of Baghdad’s difficulties in getting a firm grip on the 600-km (375-mile) desert boundary.