Amid their many capacities, none of the current or planned U.S. infantry robots is armed—yet. Armed robots are hardly new, of course, with South Korea deploying sentry gun-bots in the demilitarized zone fronting North Korea and various countries flying drones equipped with a variety of weapons.

“Just strapping a conventional weapon onto a robot doesn’t necessarily give you that much” for ground troops, said Bielat, the Endeavor Robotics CEO. “There is occasional interest in weaponizing robots, but it’s not particularly strong interest. What is envisioned in these discussions is always man-in-the-loop, definitely not autonomous use of weapons.”

Yet, depending on one’s perspective, machines that kill autonomously are either a harbinger of a “Terminator”-style dystopia or a logical evolution of warfare. This new generation of weaponry would be armed and able to “see” and assess a battle zone faster and more thoroughly than a human—and react far more quickly. What happens next is where the topic veers into a moral, perhaps existential, morass.

“It seems inevitable that technology is taking us to a point where countries will face the question of whether to delegate lethal decision-making to machines,” said Paul Scharre, a senior fellow and director of the technology and national security program at the Center for a New American Security.

“If we went to war and no one slept uneasy at night, what does that say about us?”

Last year, 116 founders of robotics and artificial intelligence, including Elon Musk, the billionaire founder of Tesla Inc. and SpaceX, sent a letter to the United Nations urging a ban on lethal autonomous weapons.

“Once developed, they will permit armed conflict to be fought at a scale greater than ever, and at timescales faster than humans can comprehend,” the letter stated, warning of a “Pandora’s box” being opened with such systems.

To date, 26 countries have joined calls for a ban on fully autonomous weapons, including 14 nations in Latin America, according to the Campaign to Stop Killer Robots. Notably absent from this list are nations with robust defense industries that research AI and robotics—countries such as the U.S., Russia, Israel, France, Germany, South Korea and the United Kingdom.

The campaign was launched five years ago by activists alarmed at the prospect of machines wielding “the power to decide who lives or dies on the battlefield.”

“If you buy into the notion that it’s a moral and humanitarian issue—that you have machines making life-and-death decisions on the battlefield—then it’s a very simple issue,” said Steve Goose, director of Human Rights Watch’s arms division and a co-founder of the campaign. “People have a sense of revulsion over this.”