On December 15, 1979, the Iranian Hostage Crisis began when fifty-two American diplomats and citizens were taken hostage at the U.S. embassy in Tehran, Iran. The crisis was sparked by the U.S. support of the Shah of Iran, who was overthrown in the Iranian Revolution. The hostages were held for 444 days, during which the U.S. attempted multiple rescue missions and imposed economic sanctions on Iran. The situation brought U.S.-Iran relations to a new low and led to a shift in U.S. foreign policy. The hostages were eventually released on January 20, 1981, just after President Ronald Reagan took office.