Perhaps the answer will be a North Korea underground nuke test. Iran may then claim to have a similar nuke from the North Koreans.
An Islamic nuke in the hands of Iran would increase Iran's stock in the world considerably.
I think you may have something there. Iran could then claim to be a member of the nuclear weapon club without directly provoking the U.S. by conducting their own test.
Or decrease it, depending on how you look at it.