They could not or they would be. Mil have their own PETF as there is space in the UHF band - but not in VHF. There may be interference with 'some communications' however the D&D cell manages the scenario; if 'some communications' is more important the practice is halted, if on the other hand it's the Guard Police or some football scores they are told to sod off so yes it may interfere with that.