' Abstract Over the years, economic sanctions have become frequently used by states as a foreign policy tool. Economic sanctions are restrictions placed on a country in order to change an undesirable behavior. States and international organizations impose sanctions in order to alter the behavior of states that violate international norms or threaten their interests. This thesis explores the effectiveness of economic sanctions as a foreign policy tool. It discusses how effective economic sanctions are in achieving their goals by using North Korea, Russia and Iran as case studies. There are several arguments concerning the effectiveness of economic sanctions. International relations experts like Shagabutdinova and Jeffery argue that most of the time, economic sanctions don't achieve their aims and end up producing a "rally around the flag" effect (Shagabutnova & Jeffery , 2007, p. 60). Others like Lowenfeild strongly believe that if policymakers are patient enough, they would see that economic sanctions do work (Lowenfeld, 1990). Oxenstierna and Olsson argue that there are international and domestic factors that increase or decrease the pressure on target states to change their policies. These factors are the regime type, the number of sender states, international legitimacy of sanctions, cost on target states, the duration of the sanctions and level of trade dependency Etc. (Oxenstierna & Olsson , 2015, p. 25). The main conclusion of this study is that economic sanctions work if they are done strategically and certain factors are taken into consideration. For economic sanctions to work, these factors have to be taken into consideration in order to fill the loopholes so target states have no other option than to change the undesired behavior. Sender states also have to be flexible when imposing economic sanctions by using the "carrot and stick" approach in order to make target states want to comply. Most of the time, economic sanctions are imposed on authoritarian regimes and because these regimes are less sensitive to sanctions, policymakers have to be patient and strategize properly in order for economic sanctions to achieve their goals. Key words: Economic sanctions, Foreign policy tool, North Korea, Iran, Russia, Sender, Target, States '