The "casus belli" of the invasion was likely the dire economic situation Iraq was positioned with in 1990. In January 1979, the Iranian Shah monarchy was overthrown and replaced by the supreme leader, Ruhollah Khomeini. To prevent the spread of Iranian Islamic extremism and other hegemonic claims of the Shatt Al Arab waterway, Iraq invaded Iran on the 22 September 1980. The Iran-Iraq war was a devastating conflict that killed more than one million individuals. The war resulted in the Iraqi army becoming the fourth biggest in the world but also devastated its economy. Iraq owed $35 billion in short-time high interest loans and the cost of infrastructure damage amounted to over $230 billion. In February 1989, Iraq established the Arab Cooperation Council which attempted to garner economic support. In 1989, Iraq provided financial aid to Jordan by providing free shipping. In 1989, Saddam accused Kuwait of oil slant drilling under Rumaila oil field on the Iraqi border. In February 1990, Saddam Hussein believed that Iraq should be compensated for protecting the Middle East from the spread of radicalism. He suggested that Kuwait, Saudi Arabia, and the United Arab Emirates (UAE) should write off Iraq's wartime loans. Kuwait and UAE did write off some of their loans. Saddam also hinted at his idea to invade Kuwait by saying, "Let the Gulf regimes know...that if they will not give this money to me, I will know how to get it." On the 18th July 1990, Saddam accused Kuwait and the UAE of exceeding Oil and Petroleum Exporting Countries (OPEC) quotas and requested that they lower their production. Iraqi Foreign Minister Tariq Aziz said, "every $1 drop in the price of a barrel of oil caused a $1 billion drop in Iraq's annual revenues." It is estimated that Iraq lost $14 billion as a result of Kuwaiti overproduction"." These factors resulted in Iraq's terrible economy. The invasion meant that Iraq owned 20% of OPEC.