All this breast beating over the idea of occupation. Suppose it is a bought-and-sold conquest in which the frog discovers the lethal temperature too late to jump from the pot? Indeed, a conquest in which the frog believes it is enjoying hot tubbing with all the consumer comforts until it is too late?
That's my assumption for the premise of the story.
OPEC oil embargo II, the U.S. economy crashes, and Middle Eastern Oil Money buys up a bunch of stuff cheap, whatever U.S. political and business interests that are still standing get friendly with Muslim Big Oil... and the U.S. was flipped that way.
Plus I think at the "darkest before the dawn" moments before it was "morning again in America" with Reagan, just the general lack of patriotism and the "malaise" made it seem more probable, and require less suspension of disbelief. Also, while Israel had already kicked ass in the 48 founding war, the Yom Kippur war, six-day war... they were only still 32 years old as a nation in 1980. While displaying massive military prowess, they hadn't such a long track record of
enduring.
Nor had we decimated and/or invaded what was presumed to be one of the most organized and powerful Muslim nations, Iraq
twice and did it in a week both times. Even in '91, don't forget all the wailing and gnashing of teeth that while we'd "win" it would be a "bloodbath" and "a thousand times worse than Vietnam" etc. in the mainstream media.
While Iran remains untested, the general idea that most anywhere in the ME will fold like a cheap suit if invaded by a competent combined-arms military wasn't established yet.