Finally, in 1979, a popular revolution in Iran swept the Shah from power, replacing him with an Islamist government engineered by Khomeini, who returned triumphantly after 14 years of exile to take his place as Iran’s political and religious leader. U.S. President Jimmy Carter, against the advice of some of his advisers, declined to act in support of the Shah, but also failed to reach out to the opposition—a decision that would cost him dearly. That October, after it was announced that the Shah, now in exile in Mexico, was suffering from an aggressive form of cancer, Carter reluctantly decided to allow him entrance to the United States for treatment on humanitarian grounds. The decision sparked a firestorm of anti-American sentiment in Iran, culminating in the students’ siege on the U.S. embassy in Tehran on November 4. The Iran hostage crisis would bring the United States to a state of near war with Iran and torpedo Carter’s presidency.