Iran's 1979 Islamic revolution, though, sent relations between the two nations into a tailspin. Shah Mohammad Reza Pahlavi was ousted, and the new supreme leader of the Islamic Republic of Iran, Ayatollah Ruhollah Khomeini, pursued a policy of standing up to "arrogant" world powers. During his regime, the United States became known in Iran as the "Great Satan," and Israel as the "Little Satan."
Even so, limited cooperation between Israel and Iran continued into the 1980s. But later a hostile rivalry emerged as Iran built up and funded proxy militias and other groups in Syria, Iraq, Lebanon and Yemen. A shadow war between Iran and Israel grew over the years.
copied npr.com, How Iran and Israel became arch enemies by Peter Kenyon April 12, 2024