The CIA was a mistake

Explanation: The populist politician Mohammed Mossadegh, during his tenure as Prime Minister of Iran, came into conflict with the UK. Mossadegh did not regard the insane colonial-era concessions to the UK to extract Iranian oil as reasonable, and attempted negotiations for a more mutually beneficial, rather than exploitative deal. When negotiations failed, he simply revoked the concessions and told the Brits to get the fuck out. The UK asked the USA for assistance, but the Truman administration was generally cautious about any action that might seem too ‘colonial’, and so declined to help.

In 1953, with the election of a new administration in the US, the previously ambivalent American foreign policy changed to strongly anti-Communist - and anti-Mossadegh, since the UK had painted him as ‘weak’ against the Communist Tudeh Party. The USA and UK then executed a coup which restored the powers of the Shah, who promptly acted as a good little puppet for the USA and UK, repressing his own people and being pliant to Western economic requests.

… until he was overthrown by his own people in 1979.