fortunately its a tiny bit more complicated than that and certainly arguable.
the sunni's (whabbi sect) hate the shia's. Before his demise Bin Laden declared and threatened to make war with Iran for not being true to the faith. Yes he called for the extinction of Israel and the western world.
Ronald Reagan, George Bush(s) clearly understood this and used it to "artistic" advantage. ex: 7 year war between Iran and Iraq was really shia vs sunni. Bush senior keep Hussien in power to keep Iran in check. Bush junior makes war with Iran to keep them from attacking the mainland. Jr gave them a playground to whack each other off
Not popular and many will disagree, but in its simplest form that was the result.
Indulge me and I will give an example of the hatred involved. In Saudi Arabia they hire expats (western) to fly and work in their airline industry. But you will NEVER see an Iranian flying their planes. (well their is 1 they do/did but it is an exceptional and unusual matter)