“Last year, U.S. Army Chief of Staff Gen. Ray Odierno predicted that Syria’s rebels would soon be victorious over President Bashar al-Assad’s iron regime without the direct intervention of American troops. One year later, as Syria’s worsening civil war has morphed, so has the challenge of tracking from afar who’s who among a disparate network of fighting forces now numbering roughly 8,000 strong and growing, according to the top U.S. commander for the region.”
Source: Number of Foreign Fighters in Syria Jumped from 800 to 8,000 in the Past Year – Defense One
