To be fair to Brother McTerrorhair, though, his original plan seems to have been to smuggle the highly enriched uranium fuel rods back to the Islamic Republic of Kablooiestan and turn them into a full-fledged nuclear bomb, at which point he can tell the Americans to take their demands and go piss up a rope. (Note the instructive real-life difference between Kim Jong-Il–probably has some really crappy nukes; is still absolute ruler of his little corner of hell–and Saddam Hussein–didn’t actually have nukes, dead at the end of a rope).
Plan B, setting off a “dirty bomb” in New York City, is a totally different affair. (In real life, a “dirty bomb” probably wouldn’t really be that effective; more of a Weapon of Mass Inconvenience than a true Weapon of Mass Destruction, whereas even a smallish nuke would be worse than 9/11.) Not the least of which, it’s a suicide mission; Backstabbing Brother wants to be President of the IRK, not a Glorious Martyr. From the point of view of his country’s national interests, having a nuke or two is a powerful deterrant against American action against his country, and allows it to resist American pressure; setting off a terrorist attack in NYC guarantees that the full weight of the American war machine comes down on his country (which he seemed to be trying to point out before pretending to go along with Plan B).
(As an aside, in the 24-verse Americans have now experienced two hostile nuclear detonations on U.S. soil, one of which only killed the one guy who was dying anyway, but the second of which actually took out an American suburb and killed thousands if not tens of thousands of people. I can’t decide if that would make Americans completely screamingly hysterical about anything “nuke”-related, or totally blase–“Oh, what, a ‘dirty bomb’ attack? Cripes, that’s nothing compared to Valencia. Freakin’ amateurs!”)