Also people have been flying remote controlled aircraft since the 50's. You don't need a super-duper autonomous gps guided drone when you can just stand on the roof with the remote. Just look at how they use IED's and cell phones.
All of this raises the inevitable question: If a robot does the killin', does it get 72 virgin sexbots?
Remote detonation via signal wire is replacing cell-activated IEDs.
You can counter a radio signal, but not a hard wire that is inactive till it is tripped. Think of those old TNT levers that set off some old movie explosion, with the wire coiling away from the bomb.
Those lines are buried for kilometers. Someone on a phone calls the person who is going to trip the bomb right as the convoy approaches.
It is a really hard problem to counter. The best detection rate will likely be from a vision algorithm that can detect changes in the dirt around some garbage pile used to cover a IED. That kind of vision algorithm is extremely hard to make.
Either way, bombs are already automated. Even third world countries make use of the most vicious robot in the world, requiring no recharge, and lasting for decades: land mines.
About 6 years ago I worked on my own "Battlebot." The thought of mounting a camera and a machine gun to the thing certainly crossed my mind as a simple "lifeless soldier" option for the military.
