I think an EMP can be triggered by things other than a bomb.
Other forms of electromagnetic warfare also exist which target the drones wireless signal to the operator. Some tanks now have these devices mounted to them. This is being countered with the use of fiber optic canisters with huge lengths of hair-thin fiber cable coiled inside. The drone would still likely be susceptible to an EMP, but as you stated an EMP is really not practical, as it disrupts all electronics even your own.
Please start with Maine and New Hampshire, I have been practicing my accent for years.