Probably not TOO hard, but the main issue there is the communication would not be reliable enough for something real time that had a low failure tolerance, like controlling a plane. If some packets got dropped and had to be re-sent, it could mean that the plane crashes if the communication was some sort of emergency time-critical maneuver.

The plane would have to be programmable and would have to support a semi-automated flying mode. Then there won't be a need for a high-capacity realtime data stream.

But then the plane would have to have obstable avoidance, auto-pilot, and it must return back to within radio range if it flies too far.

"it could mean that the plane crashes if the communication was some sort of emergency time-critical maneuver."

You don't need a very quickly-responding plane to have a large impact on military tactics.

That's where the autopilot comes in.

Far more difficult than deactivating/destroying the cell network.

Deactivating AT&T's 3G network just requires more than 10 iPhones in one room :)