Since the Islamic Revolution in Iran, political Islam has witnessed a historic rise and clashed with the U.S. Influenced by the Western academia and policy studies circles, the U.S. held a negative attitude toward political Islam. On the one hand, the U.S. attempted to contain radical political Islam and combat Islamic terrorism. On the other hand, the U.S. took a limited engagement policy toward moderate political Islam, but still tried to prevent it from gaining power through elections. After the Gulf War, radical political Islam regarded the U.S. as an enemy and confronted the U.S. through terrorist means. Cultural self-defense and the U.S. support for Israel and the Middle Eastern authoritarian regimes constituted the sources of anti-Americanism by political Islam. After the Arab Spring, political Islam came to power in several Arabic countries and did not adopt a radical anti-American policy, while the U.S. took a pragmatic approach towards the ups and downs of political Islam in the aftermath of the Arab upheaval, indicating that the conflicts between the U.S and political Islam was a struggle for power and interests instead of a "clash of civilizations."