[tomjen3]

You don't have to think criminal organizations since they have little to gain from attacking public officials -- that is just likely to get too much attention.

Think China sending a drone and using it to assassinate the the president. Make it fly away and destroy itself over water or some other place where it won't be recovered.

Later on it might be possible for people like McVeight to use a drone to kill the president rather than blow up a federal building.