Single must dangerous advancement since Atomic Weapons
The US's plans to automate as much as possible the execution of modern warfare is possibly more dangerous than nuclear proliferation. As a war with out consequence (ie. loss of human life) for an aggressor is a very dangerous thing indeed. Think about Vietnam, it still could be going on now if hadn't been for the thousands of body bags coming home to America.
If this was taken to far it could be very dangerous, who well question the actions in a fiercely nationalistic country like the US when there is no preceived cost.
Some thought has to given to this on an international level before things get out of hand, its not RotM i'm worried about its the humans that can send them out to do their bidding whilw they sit in relative safety that worries me.