Factionalism.

This is coolbert:

Originally as I had seen the headline it was that a senior Islamic State [ISIL] commander was killed.

NO! A senior military commander of a rebel faction as in opposition to Assad and having pledged allegiance to ISIL killed.

Death by suicide bomber. That attack perpetrated by the Al-Nusra front evidently. Al-Nusra either directly or indirectly that element of Al Qaeda fighting in Syria.

"ISIS-linked Syrian commander killed by rival faction"

"The leader of a militant Syrian faction that had pledged allegiance to the Islamic State of Iraq and Syria (ISIS) group was killed on Sunday in a suicide attack by rival extremists"

It is safe to say that in the entire five-thousand year recorded history of warfare [give or take a few centuries] there has never existed both on the ground and in the air a more complicated situation as what now exists in Syria? These rebel factions don't like Assad but quite often don't like one another either.

coolbert.