"Washington's geopolitical interests are key to America's relationship to Iran and the Middle East in general. The US desires to control - or at minimum to keep out of "unfriendly" hands - the immense oil reserves possessed by Iran and neighboring Iraq. It fears a future alliance between these resource-rich developing countries, which also happen to be the only two nations in the world governed by Shi'ite Muslims. The US invaded to overthrow the "unfriendly", Sunni-backed Iraqi government of Saddam Hussein. But it can neither rely totally on its selected successor regime in Baghdad, nor has it yet been able to remove the theocratic government in Tehran, which is conservative domestically but puts forward an anti-imperialist foreign policy that drives the world's remaining superpower to distraction."
Bingo.
Bingo.