If Iran left the NPT it would find it harder getting hold of the technologies they need. Israel would like to replace Dimona but as its not member of the NPT there are not many if any countries who will sell Israel either a whole reactor of the things is needs to build one itself. As long as Iran denies its developing nukes until the time comes to announce to the world it has the things and probably pull out the NPT then they can find people who will sell them the hardware they need. Isn't it more logical to play innocent and have people sell you the things you need rather than play tough pull out the NPT and say we want nukes.
Motorcyclist in his 20s dies after crashing near Gedera (Haaretz)