Here's an idea I heard put forth because Iran is asking for a great power guarantee against future incidents like this.

Have China the guarantor, build military bases, and put them under their nuclear deterrence umbrella. Iran can be assured they won't be bombed, the West can be assured they won't have nukes. (in theory, I largely assume the CCP will not aid in their construction or let them have nukes under such an arrangement).

Thing is, all the little countries are looking at what happened to Ukraine (who gave up their nukes), Iran (who has not gotten them yet), and North Korea (who has them). Their looking and thinking, if I had nukes, I probably wouldn't be the target of regime change.

Why would China agree to that? It's an insane proposition for them. "You have to put bases in a country where you have no strategic reason to do so, and in addition, you agree that if that country is attacked then you have to nuke the US, guaranteeing your own destruction."