NBC News reported in December that ISIS and Assad’s forces were mostly ignoring each other on the battlefield, focused on eliminating smaller rivals ahead of a possible final showdown.

The Assad regime was focused on stamping out the moderate and weaker opposition — and knew ISIS was doing so too. Now both are starting to engage in a “much more concerted way” because “there isn’t much of a moderate left,” according to Matthew Henman, head of IHS Jane’s Terrorism and Insurgency Center.

However, there is still one large, well-funded and well-armed obstacle acting as a thorn in both sides: the Army of Fatah, a coalition which includes the al Qaeda-linked Nusra front and recently seized control of Idlib from pro-government forces.

Analysts say the Army of Fatah also poses a longterm threat to ISIS as a competitor. Rumors are rife that the coalition is receiving funding from a variety of external actors — Saudi Arabia, Turkey and even Qatar — and Assad has had to rely on Hezbollah fighters for help in the Qalamoun Mountains to beat back the rebels.