ISIS fighters launched a significant offensive against a southern Syrian rebel base near the al-Tanf border crossing. The crossing and base are held by the US-backed New Syrian Army (NSA). ISIS fighters got into the base with a vehicle bomb and killed several fighters before detonating suicide vests.
The al-Tanf crossing is the southernmost Syrian border crossing into Iraq, not far from the Jordan border. It is considered the least important of the crossings, but was seized from ISIS earlier this year by the NSA, which in late June also attempted to seize the biggest crossing, at al-Bukamal.
The NSA forces briefly entered Bukamal, but were fairly quickly routed, and chased back to the area around Tanf. The group has been heavily backed by both the US and British governments, though they still control little territory of their own.
Today’s ISIS attack appeared to be designed to inflict casualties, not attempt to recover the crossing, and centered heavily on suicide bombings. ISIS sometimes launches such attacks in the weeks ahead of a major push, as a way to lower morale and soften heavily defended targets.