CIA - The World Factbook: Iran

Known as Persia until 1935, Iran became an Islamic republic in 1979 after the ruling monarchy was overthrown and the shah was forced into exile... Conservative clerical forces established a theocratic system of government with ultimate political authority vested in a learned religious scholar referred to commonly as the Supreme Leader who, according to the constitution, is accountable only to the Assembly of Experts. US-Iranian relations have been strained since a group of Iranian students seized the US Embassy in Tehran on 4 November 1979 and held it until 20 January 1981. During 1980-88, Iran fought a bloody, indecisive war with Iraq that eventually expanded into the Persian Gulf and led to clashes between US Navy and Iranian military forces between 1987 and 1988.