Mohammad Reza Pahlavi, the Shah of Iran, had been a reliable U.S. ally since the 1953 Iranian coup d'état. During the years after the coup, the U.S. lavished aid on Iran, while Iran served as a dependable source of oil exports. Carter, Vance, and Brzezinski all viewed Iran as a key Cold War ally, not only for the oil it produced but also because of its influence in OPEC and its strategic position between the Soviet Union and the Persian Gulf. Despite human rights violations, Carter visited Iran in late 1977 and authorized the sale of U.S. fighter aircraft. That same year, rioting broke out in several cities, and it soon spread across the country. Poor economic conditions, the unpopularity of Pahlavi's "White Revolution", and an Islamic revival all led to increasing anger among Iranians, many of whom also despised the United States for its support of Pahlavi and its role in the 1953 coup.