I listened to a story about it on Public Radio last night.
Some distinctions, I munge together from listening to other shows not directly related:
-- Pilots can suffer PTSD, disorientation, and have to reconcile being in multiple time zones, attacking and destroying targets and sometimes people (if not on simple recon flights), then leave their hangars/chairs in some Nevada control center, then go to dinner with family or friends
-- Humans in the decision loop can use morals, ethics, and surrender body language to decide to cease fire or take a chance on the surrender being a ruse, but a robot with strict survival and victor protocols/coding may be more ruthless, less forgiving, more thorough, and cause much more carnage if the program behaves in some rampage mode
-- Generals/troops (humans, if caught) can be summoned to war crimes trials/tribunals and be fined, imprisoned, or executed whereas the robots open of a whole new ethics/morality bag of worms to hash out
Also, my take on the audio report was that the concern is not robotic AUVs and missiles, but field-deployed autonomous, patrolling, searching/destroying/"engagement" machines. Not quite terminator, but more lethal than and not as benign-looking as Captain Pike/R2D2/Dalek machines.
Once gyros, accelerometers, balancers, limb controls, and running algorithms are more greatly enhanced, there will be no need for the apparatuses to help troops and marines to carry 2x or 4x the typical combat loads into the the field. These machines will be desert-capable, water-resistant, never thirsty or tired, and probably not even tracked, but maybe bipedal or some clunky-but-still-efficient multi-legged gun mounts, intel cams, and map-making netted bots.
Or, they may simply be the little bug imitators launched to spew toxic gas, release fleschette needles, or otherwise "sting" specific targets or columps of troops and perimeter guards just to grind down the morale and fighting spirit. So, my take on it is these robots might be fitted with LTL (less than lethal) but highly incapacitating and demoralizing tools. This way, even if the machines go rogue, the only likely deaths might result from the exposed who have or are:
-- adverse allergic reaction to shots, or falls from great heights
-- those who pass out near cliffs, balconies, along heavily trafficked roadways, or
-- those trying to swim in deep or forde rough water while under heavy combat loads they cannot shed, and who do not have floatation gear activated.
So, unless the bots learn to make custom ammo and deceive their (human) makers, or gain the ability to destroy aircraft, buildings, infrastructure, and ground vehicles, these robots do not all necessarily have to be totally feared as unstoppable killing machines.