The Syrian Dawud Brigade, a 1,000-strong group of fighters formerly allied to the Islamic Front umbrella, has left its position in the Idlib Province and gone to Raqqa to join ISIS.

The brigade brought with it 100 vehicles, including 10 tanks seized from the Syrian Army during various battles, and is the largest defection so far to ISIS from any rival rebel faction.

The Islamic Front’s “Sham Army” wing downplayed the reports of defection, and insisted they had expelled Dawud, believing them to be a “fifth column” for ISIS.

That seems unlikely with the faction bringing such a large amount of vehicles and weapons with them, but does reflect growing acrimony between ISIS and the Islamic Front, which has claimed to have executed ISIS fighters in recent days.

The Free Syrian Army, the pro-US rebel faction, seems to be trying to capitalize on fear of the ISIS takeover of Syria, and some of their fighters are demanding that the US dramatically increase their weapons shipments, saying they will stop fighting ISIS and potentially quit the war entirely if the US does not pony up increased aid.