The Organization of Petroleum Exporting Countries (OPEC) was founded in 1960 by five countries. The founding countries were Iran, Iraq, Kuwait, Saudi Arabia and Venezuela. The oil cartel has 13 members today. In 1973, the cartel caused the first oil crisis when it imposed an embargo on the United States and their allies for their support of Israel during the Yom Kippur War. OPEC became a key player on the oil market in 1973.