"The summer 2014 offensive in neighboring Iraq by the insurgent terrorist group known as the Islamic State (IS, aka the Islamic State of Iraq and the Levant or ISIL/ISIS) has reshaped longstanding debates over U.S. policy toward the three-year old conflict in Syria. The Islamic State controls large areas of northeastern Syria, where it continues to clash with forces opposed to and aligned with the government of Bashar al Asad. Meanwhile, fighting continues in other parts of Syria, pitting government forces and their foreign allies against a range of anti-government insurgents, many of whom also are engaged in battles with IS forces. […] For the United States and others examining options for weakening the Islamic State, these conditions raise questions about how best to pursue new counterterrorism and regional security goals without strengthening the Syrian government relative to the opposition groups and civilians it has brutalized during the conflict. Similar questions arise in relation to options for countering the Islamic State without bolstering other anti-U.S. Islamist groups. At present, anti-Asad armed forces and their activist counterparts remain divided over tactics, strategy, and their long-term political goals for Syria, with some powerful Islamist forces seeking outcomes that are contrary in significant ways to stated U.S. preferences for Syria's political future. The United Nations Security Council also seeks continued Syrian government cooperation with efforts to verifiably end Syria's chemical weapons program. As of September 2014, all declared chemical weapons had been removed from Syria, and all declared materials of priority concern had been destroyed. Related facilities are set for destruction by March 2015."
CRS Report for Congress, RL33487