Following a number of clashes in April 1969, international relations with Iraq fell into a steep decline, mainly due to a dispute over the Shatt al-Arab (called Arvand) waterway in the 1937 Algiers Accord. Iran abrogated the 1937 accord and demanded a renegotiation which ended completely in its favor. Furthermore, Mohammad Reza Pahlavi embarked on an unprecedented modernisation program for the Iranian armed forces. In many cases Iran was being supplied with advanced weaponry even before it was supplied to the armed forces of the countries that developed it. During this period of strength Iran protected its interests militarily in the region: in Oman, the Dhofar Rebellion was crushed. In November 1971, Iranian forces seized control of three uninhabited but strategic islands at the mouth of the Persian Gulf; Abu Musa and the Tunb islands.