[Suhiir]

Well a big thing with the US is that there are so damn many communications nets, and these days they're almost all encrypted and/or burst transmission, additionally the call signs and radio frequencies tend to change on a daily basis.

How the hell do you know which one to evesdrop on or jam?
If you try to scramble the thousands of frequencies the US is using at any given moment using some sort of blanket jamming you will almost invariably wind up jamming your own communications! The same applies to using some sort of EMP burst, you'd fry your own equipment as well.
Major communications links tend to use microwave or laser thus are pretty much impossible to jam or intercept.