"Lethal autonomy" for machines

The Obama administration is expanding its use of drones in the battle against terrorism.  Meanwhile, technology appears to be headed toward a time when the human role in the use of drones is dramatically reduced.  I'm not categorically opposed to the use of drones, but I am concerned that this is an instance in which a program's political popularity (Who doesn't like the idea of eliminating terrorists with zero risk to American troops?) tends to push ethical questions to the margins. Among other concerns, putting one's own troops at risk tends to focus the public's attention on the moral legitimacy of the justifications offered for the armed conflict in a way that is unlikely to happen when machines do the fighting for us.