I. Diplomatic options
These have too many moving parts not entirely dependent on only the USA, but on other countries.
1. persuasion
Carrot and stick. The book says so. But they add shouldn't use the term because Iranians might find it offensive. Kek.
Anyway.
Carrot: good deals, offering lifting sanctions, allowing them to get cool stuff and wealth.
Stick: sanctions.
As the book notes, Iran is sanctioned to the point where not much more sanctions can be placed on her, and in fact more sanctions would be detrimental to everyone else. So good luck with this. Still consequent Presidents use this doomed to fail policy over and over.
I have to point out that all these sanctions was put in place by the US's containment policy which runs in the background.
2. engagement
No sticks just carrots. Total rapprochement. Like how the US made neutral state out of China. See "ending enemy status: negotiations" >>54433
Frankly this is the actual liberal approach: lift everything, and integrate Iran into the global trade to eliminate the need for Iran to be hostile.
Problem is noone in the US sees any great opportunity in Iran, no new role they could integrate her in. Not much to gain. And even if one President thought it's a good idea, next could just revert it before the policy bears fruit.