Tensions within the insurgency that have simmered for months have intensified lately. Sometimes the disputes that erupt are centered as much on individual egos and economic resources as on ideology. Still, they inhibit the insurgency from functioning as a single fighting force. As government forces have appeared to retake control of some rebel-held territory, the schisms among the rebel groups are threatening to deepen into a new conflict that would further weaken the opposition on the battlefield.

The clashes in Dana were between rebels affiliated with the Free Syrian Army, the loose-knit umbrella group backed by the West, and members of the Islamic State of Iraq and Al Sham, the new Syria-based affiliate of Al Qaeda that includes the extremist Nusra Front. The fighting claimed many lives, according to the Syrian Observatory for Human Rights, an antigovernment watchdog group that tracks violence in the country from a base in Britain.

According to residents, activists and fighters, popular resentment toward Al Qaeda’s arm in Syria has been brewing ever since the group’s fighters, many of whom are foreigners, began sweeping into villages under the control of the Free Syrian Army and trying to impose their strict conception of Islamic law, including carrying out summary public executions.