The Iran-Iraq War began in 1980 when Iraq invaded Iran and lasted until 1988. There were several longstanding territorial disputes over the Shatt al-Arab waterway and religious and ideological tensions between the two countries' governments that contributed to the outbreak of war. Iraq's leader Saddam Hussein hoped to take advantage of Iran's weakened military and divided new revolutionary government to achieve influence in the region. The war resulted in over a million casualties before a UN-brokered ceasefire.