Here is a thought

It appears that the US has little more leverage left in the Iran situation. It occurs to me that perhaps an out-of-the-box idea may be our best bet.

Suppose the US announced that if and when Iran develops a nuclear weapon, the US will immediately supply our allies in the Middle East with working nuclear weapons (not the technology to make them - just finished, working weapons). Sounds crazy?

Consider, if Shia Iran knew that the day it masters nuclear weapons all of its Sunni neighbors would also have them, courtesy of the USA, thereby immediately neutralizing any advantage Iran might think they would gain, they might reconsider their efforts to get to nuclear weapons. They might consider themselves safer (as the lone Persian Shia nation surrounded by Sunni Arab nations that don't like them) if no one in the Middle East (including themselves) had nuclear weapons.

Consider, if Russia thought Iran's acquisition of nuclear weapons would immediately put a fully nuclear-armed Middle East on its borders, it might suddenly find it prudent to be more helpful in pressuring Iran to give up its nuclear ambitions.

Consider, if we don't give Turkey and Saudi Arabia and other allies in the region nuclear weapons, they are going to develop them on their own in any case if they face a nuclear-armed Iran. If we give them working weapons, but not the technology to make them, we still control proliferation better than if all these nations develop their own internal nuclear capabilities.

Yes, it is certainly a startling proposal. but offering it might give us the leverage with Iran (and Russia) that we currently lack.