You mean how we back-stabbed a strong ally and got a crazy enemy instead
Different perspective here;
We supported him while he was in power.
His regime was perceived as brutal, oppressive, and as an American puppet by the Iranian people.
In reality, his economic recovery plan was too aggressive, which caused food shortages and inflation.
The people revolted, and his security forces were unable to quell the riots, as there were just too many people.
You can't blame the people for their towards him and the US when we were perceived as helping to shove his dictatorship down their throats.
The US has a nasty habit of getting in offensive situations without studying the culture of the people involved.
Shame that this lack of cultural knowledge in Vietnam did not teach us anything.