Robots are no strangers to combat, and the US military is currently debating ethical questions posed by using autonomous machines in war zones. Before that even becomes an issue, though, they have to be able to actually navigate the battlefield. Reuters examines several attempts to develop autonomous load-carrying vehicles, self-driving trucks, and other support technology, noting both the progress and the substantial challenges.

Some robots, like those already used to sweep bombs, could save human lives, and others could provide a tactical advantage by letting soldiers carry more gear; none of the machines profiled are weaponized. However, experts say we're still years away from machines that can operate without human input in such chaotic environments, AlphaDog notwithstanding. "I think the layperson person thinks... you put a camera on a computer and a computer can understand that scene," says John Beck, chief engineer for unmanned systems at truck company Oshkosh. "One of the largest challenges is really getting the vehicle or the robot to understand its environment and be able to deal with it."