Robot Mule Put Out to Pasture by Marine Corps

The massive robotic mule developed by Alphabet-owned Boston Dynamics won't see combat with U.S. Marines.

LS3 (Legged Squad Support Systems) was meant to carry cargo for weary soldiers in the field. Funded by the Defense Advanced Research Projects Agency, or DARPA, the robot was capable of walking with 400 pounds of equipment on its back.

LS3 could run for 24 hours straight on a 20-mile mission across rough terrain. No controller was needed; it took visual and verbal cues from soldiers to find its way.

So why doesn't the Marine Corps want to use it? The robot's gas-powered engine isn't exactly the stealthiest piece of technology.

Watch Robots Fall Over, Again and Again and Again 1:02

"As Marines were using it, there was the challenge of seeing the potential possibility because of the limitations of the robot itself," Kyle Olson, a spokesman for the Warfighting Lab, told "They took it as it was: a loud robot that's going to give away their position."

That doesn't mean the Marine Corps is done using robots. A spokesperson from the Marines' Warfighting Lab told NBC News that LS3 was a "waypoint along a path of discovery and development" toward unmanned systems that could "lighten the load" for soldiers in the future.

"The Marine Corps isn't looking for a fair fight," the spokesman added, noting that the Marine Corps recognizes "the necessity of autonomous, unmanned, and robotic capabilities" to gain a "tactical edge through technological overmatch."