Elon Musk and Stephen Hawking are among thousands of individuals pushing for a worldwide ban on autonomous weaponry and military robots. They warn that while use of such weapons could reduce military causalities, they could also set off a global arms race and end up in the hands of terrorists and warlords. Military robots are viewed as more dangerous than drones because they can search for and engage targets without remote direction from people, and are easier and cheaper to mass produce than nuclear weapons.

At the International Joint Conference on Artificial Intelligence in Buenos Aires this week, a letter was introduced by the Future of Life Institute arguing against the use of autonomous weapons.

Among the 13,699 signatories are Steve Wozniak, Noam Chomsky, and Demis Hassabis. Executives, engineers, scientists and others representing companies such as Apple, Facebook, Google and Microsoft have signed the letter.

Experts at the conference emphasized that the deployment of military robots would be possible in years, not decades from now, so development must be cut off immediately.

According to the group’s letter: “If any major military power pushes ahead with A.I. weapon development, a global arms race is virtually inevitable, and the endpoint of this technological trajectory is obvious: autonomous weapons will become the Kalashnikovs of tomorrow.”

Many members of the group, including Hawking, have written about the potential benefits of artificial intelligence, while expressing concern regarding military applications.

“Proponents have predicted applications in fighting disease, mitigating poverty and carrying out rescues,” reports The New York Times. “An association with weaponry, though, could set off a backlash that curtails its advancement, the authors said.”