Nuclear Iran

Iran developing the nuclear bomb is an issue that hasn't gotten a lot of attention lately. I'm sure the Irannians appreciate this. Here's a decent article on the topic.
Given that trying to inhibit technological advance is not a strategy that's likely to be succesful in the long term, what should we do? I suggest that we need to start ramping up development on technologies to identify nuclear materials. Such technology could be put to two uses. It would be nice to be able to detect a nuclear warhead through any kind of shielding that a terrorist might employ in trying to gain entrance to the US (or other country for that matter). Also useful would be the ability to identify the origin of a warhead. It seems reasonable that any fissible material should be tracable to the plant it was produced at (possibly via unique trace impurities). Then, if a warhead was ever detected in the US (or more happily, detected as it was trying to gain entry), we could tell the source of the fissible material that they will destroy the offending plant now or we will send a gigaton of our warheads to do the job (in case it's buried under Mt. Everest). Ideally we would figure out a way to identify the warheads and characterize plants via satellite. I'm sure that's quite a bit of science fiction right now, hence the need to get hopping. While I'm making out a wish list, a neutron momentum damping field would be good to have also.