I always go back to the original premise - did you believe that Iran had enriched uranium to 60% or not?
Not according to the reports that they obliterated there nuclear program, no. They then confirmed that they had it buried under a mountain that only the us or china could extract, so I do not believe them. They have said multiple different things and the 60% would justify (or attempt to) attacking them, much like weapons of mass destruction. I also, don't see how them having that is any business of the US, they were sticking to the agreement then they ripped it up, of course they can do as they please, they are a free nation.
I have a hard time trusting anything coming out of this admin, especially when it conflicts with previous intelligence and intelligence from the international community.
Diplomatic means were not truly attempted.