U.S.-backed Syrian rebels have been ousted from their strongholds , monitors say . They say some , linked by family , have defected to al - Qaeda . There are reports that al - Nusra might target a key crossing at the Turkish border . Like ISIS , al - Nusra Front is trying to establish an Islamic state , though primarily in Syria .
U.S.-backed Syrian rebels have been ousted from their strongholds , monitors say . Reports say moderates , pressured by family , have defected to al-Nusra . There are concerns that al-Nusra might target a key crossing at the Turkish border . Like ISIS , al-Nusra Front is trying to establish an Islamic state , though primarily in Syria .