The U.S. military is supporting research for a mind-controlled prosthetic arm that is surgically implanted into the user's body.

"This is the most advanced arm in the world," Johnny Matheny, who lost his left arm to cancer in 2008 and demonstrated the robotic arm for DARPA, said in a statement. "This one can do anything your natural arm can do, with the exception of the Vulcan V. But unless I meet a Vulcan, I won't need it."

Matheny showed the arm during Demo Day for the Defense Advanced Research Projects Agency, the military's research unit, which was held Wednesday at the Pentagon. The device was developed at the Research and Exploratory Development Department at Johns Hopkins Applied Physics Laboratory.

The robotic arm is attached to a piece of metal that is surgically implanted into the bone of the user's arm in technique called osseointegration. Matheny is the first person in the U.S. to have undergone the procedure, according to the U.S. Army.

The Army called the system a "true man/machine interface."

The mind-controlled aspect of the arm comes into play via the nerves and muscles in what remains of the user's arm. Those tissues send signals to the robotic arm, which responds to them as a real arm would.

"This is part of the Revolutionizing Prosthetics Program, where we set out to restore near-natural upper extremity control to our military service members who have lost limbs in service of our country," said Dr. Justin C. Sanchez, director of the Biological Technologies Office at DARPA, in a statement. "The goal is to control the arm as naturally as possible."

The robotic arm, according to Sanchez, has the same size, weight, shape and grip strength as an adult biological arm.

The army said Matheny had to undergo procedures to "re-map" the nerves in his arm so he could better control the robotic limb. The military did not say what those procedures were or how invasive.

"So far this thing works great," said Matheny. "It's the arm of the future. This arm here, it can do 45 pounds. I can take on any one of these big old burley soldiers around here. We'll get a 45-pound weight and keep going. I can keep going till the battery wears down. And when I feel it starting to go down, I say swap me out. They take it out, pop another battery in, and I keep going. I never miss a beat."

Sanchez noted that researchers are continuing to push to develop more complex and powerful mind-control solutions for prosthetics and are looking into direct neural interfaces.

That kind of control would require implants in the brain. However, the implants would be able to send and receive signals so users' would gain "feeling" in their robotic arm.

"If you really want to get to natural control, you have to do this -- where we have human subjects have direct neural interfaces in their brain," Sanchez said. "They can think about moving their robotic arm and the signals come directly out of their brain, process in the arm, and can actually move the arm."