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The United States had diplomatic relationship with Iran from 1883. However, the relations between these two nations grew bitter since then. Iran supported the United States and was ally, until 1979. After Ayatollah Khomeini took over Iran, he cut off all relations with the United States. In November, 1979, terrorists captured US embassy and kept hostage everyone in it for over a year. Since then the relations between the United States and Iran went downhill. Currently, the United States government prohibits nearly all trades and investments between Iran and U.S. except for food, medicine and medical devices. The reasons for poor relations between the U.S. and Iran is because of Iran’s sponsorship of terrorism, its refusal to cooperate with nuclear program policies and human rights violation. The United States and Iran don't have a formal embassy on each other’s territory. Instead of exchanging ambassadors these two nations rely on other nations to represent their interests. Swiss embassy represents the United States interest in Iran and Embassy of Pakistan in DC represents Iranian interest in the United States (“Iran” 2013).