The thing you can do with them that would really screw things up is EMP from a high altitude detonation or even worse a sufficiently spaced series of them.

Say goodbye to the modern world & most of its people. 

 Follow it up with another a few weeks later to take out what is no longer in a farady cage for good measure. 

 If I were them, that's exactly what I would do first, then follow it up with the rest.