I never said our troubles with Iran started in 1979.
However, we had friendly relations with Iran during the rein of the Shah.
In many of these Islamic sh!t-holes the U.S. doesn't have friendly relations with a country. Instead, we simply end up taking sides in a civil war. That only works as long as we can pretend that there's no real internal opposition to the ruling government.
Look at Syria, for heaven's sake. We were a de facto "ally" of ISIS in that debacle.
Yep, ‘the Shah might have been a bastard, but he was our bastard’.