evidence: Tensions between Iran and Iraq began almost immediately after the establishment of the latter nation in 1921, in the aftermath of World War I. By the 1970s, one enduring source of conflict involved control of the Shatt al-Arab, the waterway formed by the confluence of the Tigris and Euphrates Rivers, the southern end of which forms the border between the two nations. Signed in 1975, the Algiers Agreement reduced Iraqi control over the waterway in exchange for Iran’s withdrawing support for a Kurdish insurgency in northern Iraq. A turning point occurred with the Iranian Revolution of 1978-79, which toppled the pro-Western government of Shah Mohammad Reza Pallavi in favor of a fundamentalist regime led by Shi’ite Muslim cleric Ayatollah Ruhollah Khomeini. Saddam Hussein, who became president of Iraq and leader of the country’s Ba'ath Party in July 1979, counted on the support of his nation’s minority Sunni Muslim population, and feared an expansion of Iran’s revolution to Shi’ite-dominated Iraq. Saddam also sought to overturn the border agreements of 1975 and reassert control over both sides of the Shatt al-Arab, Iraq’s only access point to the Persian Gulf.