Jimmy "Peanut Head" Carter pulled the plug on the Iranian Monarchy and allowed the Islamists to start their reign of terror.

You seriously think the USA could have crushed an extremely popular revolution and reinstated the Shah who was detested by the oiverwhelming mass of Iranians?

It would have been a bigger operation than the Vietnam War and probably with even less hope of success. Reagan's ally Saddam Hussein, with massive military forces right next door to Iran, wasn't able to do the job, even using poison gas.

Like many popular revolutions, Iran's went seriously wrong in all kinds of ways, but its mass support at the time, and later, is beyond doubt.