Recent declassification of EMP studies by the U.S. government has begun to draw attention to this dire threat. Rogue nations such as North Korea (and possibly Iran) will soon match Russia and China and have the primary ingredients for an EMP attack: simple ballistic missiles such as Scuds that could be launched from a freighter near our shores; space-launch vehicles able to loft low-earth-orbit satellites; and simple low-yield nuclear weapons that can generate gamma rays and fireballs.
http://www.wsj.com/articles/james-woolsey-and-peter-vincent-pry-the-growing-threat-from-an-emp-attack-1407885281 - April 2014
When this topic came up a year or two ago, some Freepers were poo-pooing the very possibility of an EMP attack, and saying that preparing for such an event was just a way of justifying increased federal meddling in local utility companies.
I suspect Iran has the software to simulate the results of the nuclear material they have for a EMP type reaction. They do not even need to do a test.