They have been focused on defeating their common enemy.
For almost six years, opposition armed groups in Syria have had two main objectives: seizing control of government territory and forcing President Bashar al-Assad to give up power.
Recently, rebel forces have suffered heavy losses.
Demoralised, weakened and forced from most areas they used to control, they've turned on each other.
Fighters from one of the main groups, Jabhat Fatah al-Sham opened fire on two other powerful factions Ahrar al-Sham and the Free Syrian Army.
The infighting is seen as strengthening forces loyal to the Syrian government.
Is it the beginning of the end for the opposition? And is the rivalry bringing President Assad closer to victory?
Presenter: Hashem Ahelbarra
Louay Safi, Syrian National Council former spokesman.
Can Kasapoglu, Defence analyst, Centre for Economic and Foreign Policy Studies, Turkey.
Joshua Landis, Director of the Center for Middle East Studies, University of Oklahoma.
Source: Al Jazeera News