Quote in Businessweek:
Foreign fighters began trickling into Syria a few months after the uprising against Assad began in March 2011, according to Ammar Abdulhamid, a Syrian dissident who is a fellow at the Washington-based Foundation for Defense of Democracies. Most of the opposition is made up of Sunni Muslims while Assad belongs to the minority Alawite sect, an off-shoot of Shiite Islam. Not all the foreign fighters are extremist or al-Qaeda affiliates. Some are moderate Muslims or liberals, driven by romantic notions and a sense of Arab solidarity, Abdulhamid said. …
The overwhelming majority are considered “dead weight,” said Abdulhamid. Tensions between rebels and foreign fighters mean that “oftentimes, foreign fighters stay in separate camps with a few like-minded Syrian recruits who help them secure their basic needs from nearby villages.”