The six largest Islamist rebel factions in Syria declared a new Islamic Front on Friday, forming the largest alliance of opposition fighters yet in the 2-1/2-year conflict.

Syria’s fractious rebel forces have tried many times to unify their ranks and failed. Islamist rebel commanders, in a video aired on al Jazeera, said their new union would not only seek to oust President Bashar al-Assad but establish an Islamic state. […]