Iran has many reasons to hate and distrust the US. We overthrew their democratically elected government in 1953 in order to steal their oil with a criminal CIA stunt called Operation Ajax. Then we installed the Shah. We gave Saddam chemical weapons that he used on Iran in a long and bloody war. We shot down one of their passenger airliners and Bush ran his ignorant mouth about them. And.. let's not forget that treasonous moron John McCain singing "bomb bomb bomb - bomb bomb Iran".
Had we not fucked with Iran and the Middle East the region would have most likely become democratic but after we fucked with them they turned to radical Islam.
Related: The 1953 Iranian coup d'état, known in Iran as the 28 Mordad coup, was the overthrow of the democratically elected Prime Minister of Iran Mohammad Mosaddegh on 19 August 1953, orchestrated by the United Kingdom and the United States.Wikipedia
