EMP threat

A missile went up last night not far from me; it is supposed to have been a rather large one, and according to reporters at the Pentagon, they have no clue who launched it.

I've long wondered about this scenario: Iran or some other group of not-friendlies gets nuclear weapons. They perform an underground test to which foreign observers are invited. They show those visitors the size and weight of the bomb. They then have a successful detonation. Next, they put a payload of exactly that size and weight onto a missile and fire it from land or sea, shoot the missile up in the air, and they have it harmlessly go boom at altitude. That nation would have demonstrated the ability to take out a large segment of the world with a single EMP weapon.

So, who launched that missile yesterday?