Where? Israel? They don't have any oil. We have had bases in Saudi Arabia since the 80s because they were one of the more stable Middle Eastern nations and because they were extremely anti-communist which made them good allies at the time. If you want to insist we were there for oil then we were there to make sure the Soviets didn't get their oil. We expanded our presence there during the Gulf War because they have a border with Iraq and maintained that expanded presence until 9/11, at which point it expanded further to serve as a hub for Middle Eastern operations.