Iran has been a troublesome state for the West since the Iranian revolution of 1978 deposed the Western-oriented Shah, Muhammad Reza Pahlavi. Ayatollah Ruhollah Khomeini, who emerged eventually as the unchallenged leader of revolutionary Iran, preached a messianic form of Shi’i Islam that he conceived as waging a continuous struggle against the forces of evil, which he associated with the infidel West, and particularly with its leader, the United States of America. Since that time, Iranian leaders have frequently defined their foreign policy as being inimical to the West, or at least to the United States, and have carried on an aggressive struggle against it. Obviously, that struggle has taken a wide variety of forms, and at times Iranian leaders have shown a willingness to ratchet down the level of confrontation. At no time, however, have Western relations with Iran been trouble free.