So what options the US really has?
They always do the Containment in the background, but beyond that...
In my opinion real solution would be the Engagement, this most likely would work, and this would pull the poison teeth out - even if they acquired nukes.
But the US would not do that, unless circumstances change a lot. What she is willing to do is just Persuasion, and as recent events proved: they found a way to do an airstrike (probably result of decades long preparatory work) which was a combination of Israeli one with a fly-in fly-out US participation. So it was barely a US airstrike.
Anything else don't seem to be a real possibility. Invasion? Revolution? Insurgency? Coup?
In the past 45 years this is what the US did: containment and in the layer above trying to persuade Tehran occasionally. And now the airstrike - which is a huge exception, like a rare astronomical event, and only good for delaying the inevitable.
Will things change? Did recent events opened up some of the paths - like an insurgency of a minority? Did it closed surely other options - such as the rally round the flag effect blocked a chance for a revolution?
And put it in global perspective: how feasible would be to do some other moves: consider the threat at Taiwan would the US spend resources on an invasion?
And in more local perspective, would a larger turmoil in Iran shift the stability in the Middle East in the right or the wrong direction? And the book also points out: Iran acquiring nuclear weapons could also cause proliferation, if they have that, some neighbours at the gulf would also want 'em Pakistan already has.

Lot of interesting things in this book. I want to note another one: it seems the US finds everyone with nukes reasonable and trustable. The Russians, the Chinese, the British, the French, the Indian, the Pakistani, the North Korean and the Israeli are all fine but surely the Iranians the irrational ones who'd launch 'em. The authors do ask, would Iran really do? Or would Iran give nukes to her terrorist proxies? They have not gave even chemical weapons. Is there a real threat there?
Ofc it's more about that pesky proliferation. They don't mind those who have nukes, since can't do much about that, it's not a good idea to fuck with them either. But they could try prevent others to get it. If everyone had nukes, there won't be any county whom the US could bully.