In 25 years, the U.S. military will operate under the principle of "less is more."
Less manpower. More robots.
Robots on the battlefield of the future will carry a heavier load, both literally and figuratively. They will operate with more freedom and begin to think for themselves. They will be armed and take on more tasks.
"I think you'll see many of the high-risk missions done by autonomous platforms," said Tim Trainer, vice president of product management for defense and security at iRobot.
IRobot is perhaps best known for its Roomba vacuum, but it has a growing arsenal of defense and security robots—everything from a five-pound robot that can be easily tossed and even dropped on its head, to a 500-pound robot that can lift close to its own weight. A trainer demonstrated some of the robots at the company headquarters in Bedford, Mass., and he sees a future where one person can control multiple machines operating on a single software system without having to constantly monitor them.
Read MoreThe man with the Pengagon checkbook
Future robot missions will most likely include perimeter security and firefighting, but in the short term, the Army is working on supplying driverless convoys.
"I think the technology that we have is better than the Google car," said Major Gen. William Hix, deputy director and chief of staff for the Army Capabilities Integration Center in Fort Eustis, Va.
Perhaps most intriguing—or frightening, depending on your point of view—the Pentagon is considering robots that fire weapons. The Defense Department held a "robot rodeo" last fall where military contractors presented robots firing guns.
"Think of a platoon of four tanks with two to four armed robots which would of course make that formation much more lethal," said Gen. Hix. He also sees armed robots eventually riding on troop carriers providing cover and a top-level view as soldiers dismount. "The robots are in position to provide over-watch and suppress the enemy...(soldiers) are not having to fight their way off the ramp," he said.
The biggest challenge at the moment is robots need "constant supervision," said the general. "If you turn your back on them, they will often drive off in a ravine...or mistake a stream for a road."
One man to one machine is inefficient, and defense companies are working to improve that scenarior. "What we would like to do is make them much easier for the operators to operate," said Trainer.
For all the plans to arm robots, Gen. Hix does not expect an army of clones. "Armed robots will remain under the control of a soldier," he said. "There will always be a human in the loop."
What will robots look like in 25 years? Some robots being developed by Boston Dynamics, which Google bought last December, carry names like Big Dog and Wild Cat. They are eerie-looking machines that mimic animal movements. Boston Dynamics also created a robot for the Defense Advanced Research Projects Agency (DARPA) that moves like a horse.
But could robots ever look human? Tim Trainer said only if it helps the mission.
"Does the robot understand, and how would I know that it understands the commands that I've given to it?" he said. "Some facial type of expressions or emotional type expressions out of the robot are helpful for understanding and communication between the human and the machine. By the same token, you don't want something that the public is afraid of, and that will come with trust and reliability."
Gen. Hix envisions a bond between man and machine that evolves over the next 25 years.
"I would like to see the relationship between a soldier and a robot be much like a hunter and his bird dog, where there's a learning relationship between the two members of the team," he said. "The robot will respond to a soldier's hand and arm signals, and his behaviors, in the way hunting dogs do with their masters today, so the soldier is not controlling the robot. He is enabled and supported by the robot."
—By CNBC's Jane Wells