UAVs (Unmanned Autonomous Vehicles), or drones, are now available for prices as little as €300.
There have been a couple of near misses involving them:
Heathrow Airbus in near miss with drone that ghosted into Britain's biggest airport undetected by air traffic control | Daily Mail Online
A drone carrying a flag resulted in the abandonment of a match beetween Serbia and Albania:
Unlike model aircraft, UAVs are simple to operate. Their gyroscopes control the trim and other factors affecting stability. The user is merely specifying where it should be rather than altering the flight control surfaces in order to get the thing there.
They are already being used by the paparazzi as well as by the porn industry(!).
My question is as to whether terrorists will find a use for them.
Normally, model planes can only operate not only within line of sight of the operator, but also within a defined radius of the operator.
Some UAVs don't feature this limitation, though. If they are GPS enabled, they can be preprogrammed with a destination and will direct themselves there without requirement for the operator to be there. They can carry a small payload, but certainly enough to cause serious damage.
The drone carrying the flag into the football match could as easily have had a couple of kilos of primed explosive.
Will drones become a new terrorist threat?
If so, how can they be countered?
ETA: I should have included the fact that various nuclear power stations in France have reported flyovers by drones which were probably mapping the facilities. Orders now are to shoot down any seen in thee vicinty of sensitive installations.