You said -- "How can we prevent Pakistan or North Korea from nuking a country? (Hint: We can't and nobody can.)"
Oh yes you can! You might not like the answer -- but -- you can nuke them first. That will keep them from doing it. Problem solved.
And that's exactly why the article says the only solution is to do a pre-emptive strike against Iran. You attack them first (as Israel has done in several prior instances). That solves the problem until another problem crops up...
Regards,
Star Traveler