Following a number of clashes in April 1969, Iran abrogated the 1937 accord and demanded a renegotiation. In mid-1973, the Shah returned the oil industry to national control. Following the Arab-Israeli War of October 1973, Iran did not join the Arab oil embargo against the West and Israel. Instead, it used the situation to raise oil prices, using the money gained for modernization and to increase defense spending. A border dispute between Iraq and Iran was resolved with the signing of the Algiers Accord on March 6, 1975. The Iranian Revolution, also known as the Islamic Revolution, was the revolution that transformed Iran from an absolute monarchy under Shah Mohammad Reza Pahlavi, to an Islamic republic under Ayatollah Ruhollah Khomeini, one of the leaders of the revolution and founder of the Islamic Republic. Its time span can be said to have begun in January 1978 with the first major demonstrations, and concluded with the approval of the new theocratic Constitution—whereby Ayatollah Khomeini became Supreme Leader of the country—in December 1979. In between, Mohammad Reza Pahlavi left the country for exile in January 1979 after strikes and demonstrations paralyzed the country, and on February 1, 1979 Ayatollah Khomeini returned to Tehran. The final collapse of the Pahlavi dynasty occurred shortly after on February 11 when Iran's military declared itself "neutral" after guerrillas and rebel troops overwhelmed troops loyal to the Shah in armed street fighting. Iran officially became an Islamic Republic on April 1, 1979, when Iranians overwhelmingly approved a national referendum to make it so. The ideology of revolutionary government was populist, nationalist and most of all Shi'a Islamic. Its unique constitution is based on the concept of "" the idea advanced by Khomeini that Muslims – in fact everyone – requires "guardianship", in the form of rule or supervision by the leading Islamic jurist or jurists. Khomeini served as this ruling jurist, or supreme leader, until his death in 1989. Iran's rapidly modernising, capitalist economy was replaced by populist and Islamic economic and cultural policies. Much industry was nationalized, laws and schools Islamicized, and Western influences banned. The Islamic revolution also created great impact around the world. In the non-Muslim world it has changed the image of Islam, generating much interest in the politics and spirituality of Islam, along with "fear and distrust towards Islam" and particularly the Islamic Republic and its founder. Khomeini served as leader of the revolution or as Supreme Leader of Iran from 1979 to his death on June 3, 1989.