The Free Syrian Army wants to be rid of foreign fighters . They killed about 200 fighters belonging to an al - Qaeda backed group . ISIS forces have increasingly come into conflict with FSA fighters and other hard-line anti-Assad factions while attempting to enforce their strict form of Islamic sharia law on areas coming under their control across northern Syria . Other groups say ISIS responsible for executing 30 .
The Free Syrian Army wants to be rid of foreign fighters . They killed about 200 fighters belonging to an al - Qaeda backed group . Other groups say ISIS responsible for executing 30 .