Enhanced EMP weapons could cause much electronic confusion.
It may be possible to design a warhead in such a way that its ability to produce EMP is greatly amplified. I suspect that the USA has already tested such weapons underground, although I am not privy of the resutls.
Even if they work, the problem is that the result is rather omnidirectional, so one cannot point it at one modest-sized country (like Iran) without it knocking out the communication of its neighbors, like Iraq, Arabia, Kuwait, etc, etc.
David F Mayer