OK this is a topic done to death, but just like compiling the "top 10 land armies", has a certain repeat value.
Who are the suspects for having a secret nuke arsenal, and just to add more value, which are the countries you believe the world will not object if they become a nuke power?
It is interesting to note that even 14 years after declaring their nuclear arsenal, neither India nor phuckistan are "recognised" as nuclear powers.
Countries I believe already have a clandestine nuclear arsenal are:
South Korea (north korea already has nukes)
Of the above, I feel only South korea can come clean - provided of course that they have nukes in the first place.
Japan will never openly admit they have nukes (if they do) because of the stigma and taboo attached with the N-word, for get international condemnation, their own public will pull them down.
Israel also cannot declare their weapon status coz the entire middle east will go ballistic, the mullahs and ayatollahs will be jumping in the desert with fear and will lead to massive regional chaos.
Iran should have nukes, or they are extremely close. They have seen what has happened to saddam and iraq, if they confront the US now the ayatollahs would be digging their own grave. Their would be no second chance for them, so they would need some insurance. If they dont have nukes and are still sabre rattling then it only proves the theory that muslims are dumb.
Taiwan is either very brave to stand up against a bully 100 times its size or they have a nuke hidden somewhere. Though it sounds far-fetching but it is likely they have nukes just in case of a commie invasion.