Hopefully!

Although i reckon even the common kit that's been available to consumers for the past few years could be tricky to jam without concerted effort:

http://www.futaba-rc.com/technology/fasst.html

I.e. to jam this frequency hopping requires than you either a) figure out what channels to jam at what time or b) saturate the full bandwidth.

If you can do either of those, you'd probably be better jamming the voice comms than RC helis. Not sure though.

The frequency hop rate for commercial stuff is pretty low.

Presumably the military has met (and solved) this problem already, so it's just a case of getting the RF equipment small enough.