"After six years of conflict, the challenges posed to U.S. national security by the situation in Syria have multiplied and evolved. Initial unrest and the Syrian government's violent response fueled U.S. concerns about Syria's stability and civilian protection in the midst of the 2011 'Arab Spring.' The country's descent into brutal war created a multifaceted regional crisis, marked by the mass displacement of civilians, the emergence and empowerment of violent armed Islamist extremist groups, gross human rights abuses and war crimes, the use of chemical weapons, the proliferation of arms, and the covert and overt intervention of outside actors. Over time, U.S. policymakers have appeared to feel both compelled to respond to these interlocking crises and cautious in considering potentially risky options for doing so, such as the commitment of military forces or the provision of lethal assistance to combatants. The Obama Administration supported various partner forces in Syria, while calling for Asad's ouster through a negotiated transition."
CRS Report for Congress, RL33487
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html