It is a mistake to think that Israel will get away with any 'surgical' strike. The death toll from the wars in Iraq and Afghanistan runs into hundreds of thousands combined over past 10 years. And Iran is much bigger, more powerful, and has been preparing for a showdown since 1979. There will be a bloodbath for sure. And as far as I see, Iranians are going to unite behind their mullahs and attack anything within the region, with everything they have. And, as far as I see, Iranians cannot be subjugated short of the eventual use of tactical nukes against them.
And your example about N. Korea getting out of the NPT actually makes your case weaker: By getting out of the NPT, NKo were more likely to be challenged than to be given food even as they flouted their nukes. Good for NKo that Japan does not have the feared Lobby in America working for Japan. Too bad for America, Americans, and the world that a few thousand well-connected war-mongers have held the entire Congress in its firm, blackmailing vice like grip! After all, when it comes down to, 'America' policies are basically those of a few hundred Congressmen/Senators and a few dozen powerful media empires. You take hold of them, you get the country! Now, I am aware that there is a sizable fundamentalist Christians hoping for their damned Rapture but they are probably no more than 20% of the population.
The 'Liberals' in America--as evidenced in the NY Times 'Comments' over past few days--can see how this rapacious, mean-spirited, blood-thirsty Israel Lobby has managed to hijack the Congress. They are fuming over it. One day the majority of Americans will join them--and the world, including Israel itself, will be better for that.
As to Iran having nukes or not, well, it is chicken or egg! Don't have nukes means face the music like Iraq or Libya. Have the nukes then that would give 'justification' for attacks. What should Iranians do? May be make their conventional deterrence so strong that they raise the cost of war too high--perhaps the cost is too high for all anyway and that's why no direct attacks since 1979. Nukes should be weapons of no use. They should be destroyed ALL OVER THE WORLD, ASAP! But, alas, we may see some being used in our own lifetime.
[Written quickly--will try to fix the typo later...]