I hope this link works. BS my a$$.
http://www.house.gov/hasc/openingstatementsandpressreleases/108thcongress/04-07-22emp.pdf
EMP has been know about since the 1950's but unless a nation has an ICBM, there is no way to get a nuclear warhead over the United States high enough to create a continent wide EMP. Also, you would need a very large device, well into the megaton range to do significant damage. Iran doesn't have an ICBM nor do they have a thermonuclear weapon.