Maybe a firm promise that the USA and the UK will not invade Iran might be a good way of encouraging Iran to confirm that it had abandoned any plans to acquire nuclear weapons. Except who would expect anyone to believe a promise like that?

And when does Israel get required to get rid of the hundreds of nuclear weapons it is said to have stockpiled? (To say nothing of the Big Boys, notably the USA - but of course that is totally different. After all it is inconceivable that the USA could ever use nuclear weapons, especially against cities...)