[1] https://www.bloomberg.com/news/features/2016-05-30/the-untol... (https://archive.is/kRW9c)
[2] https://www.currencytransfer.com/blog/expert-analysis/saudi-...
* From [1]: “Just a week before setting foot in Saudi Arabia, Simon publicly lambasted the Shah of Iran, a close regional ally at the time, calling him a “nut.””
https://www.semanticscholar.org/paper/Showdown-at-Doha%3A-th...
The rise of Islamic Jihadis, financed by KSA and trained by CIA, propagation of Wahabism, tolerating the replacement of a secular ally in Iran with Islamist revolutionaries, ..., are all the direct consequence of this strategic shift by the USA. This is all in the context of post-Vietnam debt, rise of OPEC, and a still very menacing Soviet Union.
The Shah had made the error of thinking that by not joining the oil embargo of Arab states he was proving yet another reason (beyond being a forward Western block allied barrier to Soviet Union’s access to the Persian Gulf) for being considered a strategic ally to US. Nixon and Kissinger publicly and privately also assured of Iran’s importance. But what actually happened was that the oil embargo demanded a reassessment of the value of Shah of Iran to US. It was seen that oil and Arab producing nations’ alignment was far more important than any value Shah’s Iran was providing as a bulwark against the Soviets. The Brezhinski doctrine effectively addressed the means of filling the vacuum: Islamic Fundamentalism.