According to an article in the Army Times, the so-called 'ethical robots' would follow international laws.  Ronald Arkin, from the Mobile Robot Laboratory at the Georgia Institute of Technology, wrote a book to discuss the future of robotics.

In "Governing Lethal Behavior in Autonomous Robots," Arkin claims robotics, if programmed correctly, have numerous advantages over human ground troops.  Robots are emotionless , expendable, and can be customized for specific missions.  

It's possible the robots could be taught remorse, compassion and guilt, but exact senses the robots would be programmed with are still unknown.  Furthermore, depending on the determined level of guilt, and the mission being carried out, the firepower and effectiveness of weapons used will change.

The robots could also be used to monitor soldiers to ensure international treaties are being followed by U.S. and coalition ground troops.  Although many soldiers don't want to be monitored in such an intrusive manner, several high-profile cases of abuse and murder have further blemished the military's image among locals in Iraq.  

If funding is properly allocated for the research, it could be available in 10 to 20 years.  As the U.S. continues to fight wars using enhanced technology, unmanned aerial vehicles (UAVs) and other unmanned resources have become popular alternatives to launching manned missions -- and is expected to further increase in the future.