CBS

For several months now, we've been reporting on tech iconoclast Elon Musk's public warnings about the dangers of artificial intelligence. What we hadn't heard was just how soon AI might become a threat.

Turns out Musk, the CEO of Tesla and SpaceX, is worried that "the risk of something seriously dangerous happening is in the five year time frame. 10 years at most."

Or so Musk wrote in a comment that followed an essay by virtual godfather Jaron Lanier titled "The Myth of A.I." on Edge.org last week. A number of comments from notable personalities including XPrize Foundation founder Peter Diamandis, technology editor Kevin Kelly and author George Dyson also appeared alongside the essay. Musk's comment was quickly removed but not before it was noticed by Mashable and other outlets.

In his original comment, as preserved on Reddit, Musk cited his involvement as an early investor in the British artificial intelligence company DeepMind, now a part of Google, for evidence.

"The pace of progress in artificial intelligence (I'm not referring to narrow AI) is incredibly fast," Musk wrote. "Unless you have direct exposure to groups like DeepMind, you have no idea how fast-it is growing at a pace close to exponential."

Musk adds that leading AI companies "recognize the danger" and are working to control "bad" superintelligences "from escaping into the Internet."

It's also worth considering, as Leonid Bershidsky does here, that Musk's comments about AI this year could be about hyping the industry as much as anything else. Musk, however, wrote in his comment that "this is not a case of crying wolf about something I don't understand." He hinted further at his concerns this week, retweeting a 2009 video of DeepMind co-founder Shane Legg discussing the possibility of unsafe AI being given access to supercomputers.

Apparently, Musk had meant for his comment on Lanier's essay to be private, and it was removed from Edge.com.

A spokesperson for Musk told Mashable the comment was sent to Edge's publisher via email and was not intended for publication, adding that Musk will soon publish a longer piece outlining his thoughts on AI. Representatives for Musk did not immediately respond to CNET's request for comment.

So far, we've heard Musk compare the future of AI to the " Terminator" series, nuclear weapons and to " summoning the demon."

Now we also have some idea of the setting that Musk envisions in his nightmares -- as the world celebrates the 2020 Olympics in tech-centric Tokyo, the anxious futurists among us will be keeping an eye peeled for a sneak attack launched against us meatbags by Skynet.