The entire Middle East has become embroiled in a far reaching civil war since the Obama/Clinton foreign policy doctrine has been instituted. The cause and effect was completely predictable but the new mandarins in the US State Department (most of them just graduated from Harvard since most of the old gray haired people were sidelined) have been mystified.
As the US withdrew and what pieces it had left in the game, it bungled (maybe on purpose - difficult to say) the void was filled by exceptionally malevolent actors.
There are no mysteries in violent internal instability. If one side suddenly is losing, that always means the opposing side has received assistance. Sometimes that assistance is in the form of defections. Sometimes it is in the form of betrayals. Most often, a sudden change in fortunes means one side has received major outside military aid or an influx of soldiers that alters the local outcome.
You don't have to look farther than the American Revolution to see how that worked. It's a text book example of what we are seeing throughout the Middle East in terms of shifting balances because of outside aid and intervention.
The proliferation of nuclear weapons in the Middle East should bother us all. Israel, stable, is building them as if there was no tomorrow to increase and scatter their inventory to different locations well beyond Desdemona. Iran, buying them from North Korea, wants more than the two or three that it has -- maybe hundreds. Saudi Arabia likely has four or five, purchased at massive cost from Pakistan and Syria is begging Russia for nukes. Russia is very unlikely to comply with their request.
President Obama plans to kick off a new war in January 2017, in time for the incoming president to deal with the fall-out (nuclear or otherwise). He said, "Our troops have long shown what can be achieved with shifting objectives and no strategic foresight. If we've done it before, we can do it again!" (pre-recorded cheering in the background)