Elon Musk worries that building a general AI would be "summoning the demon."

He may want to send us all to space and make the world drive electric cars, but Elon Musk isn’t gung ho about all technologies. In particular, he’s famously uneasy about machine learning, and he has in the past gone so far as stating that he believes building a general-intelligence AI is tantamount to “summoning the demon.” Now he’s reaffirmed that message to U.S. governors, urging them to regulate AI—and quickly.

Speaking at the National Governors Association meeting in Rhode Island on Saturday, Musk called AI “the biggest risk that we face as a civilization,” according to the Wall Street Journal. That’s a sentiment shared by a small but influential crowd of techno-thinkers. Whether it’s an accurate assessment is very much up for debate, however, as Oren Etzioni, the CEO of the Allen Institute for Artificial Intelligence and professor of computer science at the University of Washington, has argued in these very pages.

Even so, Musk would like lawmakers to do something about what he sees as a huge existential threat before it becomes too big a problem. Recode recounts a rather vivid comment made by Musk at the event:

“Until people see robots going down the street killing people, they don’t know how to react because it seems so ethereal. AI is a rare case where I think we need to be proactive in regulation instead of reactive. Because I think by the time we are reactive in AI regulation, it’s too late.”

It’s inarguably worth thinking about the impact that artificial intelligence might have on the world, but to many supporters of AI it still seems too early to regulate such systems. While machine-learning software is beginning to rival human intellect at some specific tasks—such as speech recognition, translation, and identifying objects in images—joining those components into the more general intelligence that troubles Musk remains a way off.

Some of the governors were shocked by Musk’s urgency. Arizona governor Doug Ducey, for instance, said that he was “surprised” to hear a call for regulations on AI “before we know what we are dealing with.” Indeed, Musk might have a tough time convincing lawmakers, who traditionally need some sense of what needs regulating against before they will consider legislation.

Musk’s take on the situation? “Right now the government doesn’t even have insight,” he said, according to the Journal. “Once there is awareness people will be extremely afraid, as they should be.”

(Read more: Wall Street Journal, Recode, “No, the Experts Don’t Think Superintelligent AI Is a Threat to Humanity,” “Will Machines Eliminate Us?”)