This thesis is aimed to explain the factors that caused the United States’ failure in implementing the 'Responsibility to Protect' in the Syrian Civil War during Barack Obama era in 2011-2016. This study uses two theoretical frameworks, including the Foreign Policy Decision-Making theory by William D. Coplin and the concept of Responsibility to Protect (RtoP) by the United Nations. By using the concept of RtoP, this study proves that the United States conducted a humanitarian intervention in Syria, one of which was the USTurkey collaboration to build “safe zone area” in TurkishSyrian Border. Besides, using the model by William D. Coplin, this study found that the factors that caused the United States’ failure in implementing RtoP in Syria included domestic and international factors, such as the United States Congress and Americans did not supporting the intervention in Syria, the scarcity of the United States' economy and military resources, also Russia and China involvement in the Syrian Civil War until there was no international consensus, where the United Nations provided resolutions or other alternative solutions to stop the conflict.