Since the breaking of diplomatic relations between Iran and the U.S., Iran has been considered as a threat to American security, diplomacy, economy and U.S. allies. The U.S. has imposed unilateral sanctions on Iran for over thirty years over issues such as terrorism, weapons of massive destruction, human rights and so on. As an important part of American policy toward Iran, these sanctions, which are rooted in the conflicting interests between the two nations, are testimony to the changing bilateral relations. Although the sanctions have been in place for decades and created political and economic pressure for Iran, they have not achieved the desired effects. This controversial policy has caused a lot of international discontent because it affects the interests of third countries who may be punished for violating America’s unilateral sanctions.