Unfortunately IR is unique in that regard... they have made various statements regarding their intent to use nukes, including a previous president promising, in public, to nuke Israel as soon as they had the ability.

Their bluster is extreme, and while I suspect it is just bluster, Israel is simply not taking the chance... they have perfectly understandable holocaust PTSD and only have one big city, so would essentially cease to exist if they took one nuke hit.

I do not believe that IL will allow IR to progress to a bomb... they have the means to stop within hours, anytime they feel the need, and ultimately there's nothing to stop them. A one-sided nuclear conflict in the ME would arguably be worse for global stability than what's going on now. Certainly be worse for IR.