The Nusra Front, the al-Qaida affiliate in Syria, is consolidating power in territory stretching from the Turkish border to central and southern Syria, crushing moderate opponents and forcibly converting minorities using tactics akin to its ultraconservative rival, the Islamic State group.

But while the Islamic State group gets most of the attention largely because of its penchant for gruesome propaganda, the Nusra Front has quietly become one of the key players in the 4-year-old civil war, compromising other rebel groups the West may try to work with while increasingly enforcing its own brutal version of Islamic law.

Its scope of influence now reaches to the Golan Heights, which border Israel, and its membership - largely composed of Syrian nationals - refuses any negotiations with the government of President Bashar Assad, further complicating the brutal conflict.