| Syria is one of the most important countries in the Middle East. On 15 March 2011, the Syrian conflict between forces loyal to the Ba’ath government and those seeking to oust it broke out. Over the past three years, more than 100,000 Syrians have lost their lives in the conflict, which has attracted the attention worldwide. Some western countries criticized the use of chemical weapons in Syria. Especially, on August 21, 2013, the Syrian government was reported to have killed hundreds of civilians in a chemical attack, violating international law and crossing what the Obama administration had called a “Red Lineâ€. Thus, America planned military action. However, on September 14, the United States and Russia reached a sweeping agreement, which laid the foundation for a political settlement to that country’s civil war without U.S. military intervention.Causes of America’s suspension of military intervention in Syria remain to be explored, which is also the aim of this thesis. This thesis can be logically divided into four parts. The first part introduces Syrian conflict including its background information and U.S-Syrian relations since Syrian conflict broke out in March, 2011. The second part explains the causes from the perspective of America’s domestic anti-war elements, including the societal environment of America, the governmental setting in which policymaking occurs and the historical enlightenment from the previous wars that all prevent Obama’s strikes against Syria. The third and fourth part expound on the causes respectively from the perspective of Syria and other countries like Russia, China, England, Germany, Australia, etc., as the external challenges that add more obstacles to the military intervention. In short, America’s domestic anti-war elements and external challenges have motivated its suspension of military intervention in Syria in September 2013. |