Historically, al-Qaeda’s Nusra Front has gotten along with the other rebel factions in Idlib Province, so long as they don’t contest the reality that Nusra ultimately controls the area of northwest Syria. Efforts by the US to establish a “moderate” competitor in the area looked to change that.
Unsurprisingly, Nusra didn’t take too kindly to this, and before the US-backed faction, Jaish al-Tahrir, had really started to assert themselves, the group has lost its top leader Mohammed al-Ghabi, who was “injured and kidnapped” from his home in a Nusra raid.
Reports from the area say that Nusra not only captured Ghabi in short order, but also set up a series of checkpoints in the surrounding area, which seems designed to limit the ability of the Jaish al-Tahrir to mount any sort of rescue.
Previous efforts by the US to establish rebels in the same area, through training schemes, saw the first class of rebels wiped out in short order, and the second group defecting to al-Qaeda almost immediately upon entering the country, with some trading them US-provided gear in return for free passage out of the area.