There are signs that Iran may be working toward an Electromagnetic Pulse (EMP) strike on the United States.
“Once Iran has a nuclear weapon, they are ready to launch an EMP attack against us,” former CIA director James Woolsey told For the Record. "I think they have conducted launches of satellites of the type that you, and in the direction you would want for an EMP attack."
In addition to those tests, Woolsey says the Iranian military has laid the groundwork for a religious justification for an Electromagnetic Pulse strike. In 2010 a military textbook called “Passive Defense” was published. A section of that book outlines how an EMP strike would be compliant with Islamic law.
“The deaths from electromagnetic pulse are all indirect,” said Woolsey. “They come from destroying the electricity grid, and thereby not being able to operate the other 17 infrastructures in the United States - food, water, finance. Everything else operates off electricity. And by not being able to operate those, you will have lots of people die of thirst, die of starvations, die of social disruption."
“The idea, as I understand it was that since one is not directly attacking or killing humans, it doesn’t come under the stricture of some other ruling, or idea that one should not use nuclear weapons against people."
The Congressional EMP Commission spent nearly a decade studying the issue and concluded that as many as 90% of all Americans could die in the first year after an EMP strike. [source needed, the video link was invalid]