Create military robots that kill and use dead bodies as fuel. Sounds like a great idea! I'm sure nothing could ever go wrong with that. Why not give them the ability to reproduce while we're at it?
This story touches on an interesting subject though. We are quickly developing military tech to the point that wars of the future may be fought by self-aware (sentient) robots with the ability to replace the "boots on the ground." At some level, they will also have to make the same decisions as soldiers/Marines in the battle area.
I believe the use of these machines against humans would be unethical.
Our current technology requires a human to pull a trigger in order to end the life of an enemy. Even the new generation of UAVs still require a remote human operator. This means a human must determine if his actions are within the rules of warfare. Soldiers, no matter what they claim at a war crimes trial, never blindly follow orders. Robots do. War isn't perfect today and removing the inherit checks and balances of the chain of command is certain to make it less perfect tomorrow.
This quickly evolving technology could also someday place a lot of power in the hands of a select few. Soldiers are part of a collective, but are also individuals from society that share our values and ideas--they weren't built in a factory. Violating Posse Comitatus would be a problem for most soldiers. Not so for robots who will lack the ability to check the orders they have been issued against an ethical code. Combine this power with the trend towards totalitarian big government and you have a recipe for disaster.
I fully support the idea of using technology to save US lives on the battlefield, but it should never replace the role of the warrior.