Which country released 66 Americans held hostage only after Reagan became president?

Iran released 66 Americans held hostage only after Ronald Reagan became president. The hostages were taken during the Iran hostage crisis, which began in November 1979. They were freed on January 20, 1981, the same day Reagan was inaugurated, marking a significant moment in U.S.-Iran relations. This timing has led to speculation about the influence of Reagan's administration on the release.