Tesla Inc. co-founder and Chief Executive Elon Musk has made no secret of his worries about the dangers of unregulated artificial intelligence research, and today Musk criticized Facebook Inc. CEO Mark Zuckerberg for dismissing concerns about AI risks.

Musk’s and Zuckerberg’s companies are both working on the bleeding edge of AI technology, and while both agree that AI has tremendous potential for good, they disagree with how it should be pursued.

During a Facebook Live broadcast on Sunday, Zuckerberg (pictured), said he’s optimistic about AI and that some people are just “naysayers and try to drum up these doomsday scenarios.”

“I just don’t understand it,” Zuckerberg said. “It’s really negative and in some ways I think it is pretty irresponsible.”

Musk fired back at Zuckerberg’s statement in a tweet, saying, “I’ve talked to Mark about this. His understanding of the subject is limited.” Musk did not elaborate on how Zuckerberg’s understanding is limited, nor did he expand on exactly what was said during the conversation.

Musk worries about the long-term effects of AI, and he firmly believes that AI research needs to be regulated by the government as soon as possible. While speaking at the recent U.S. National Governors Association meeting in Rhode Island, Musk said, “AI is the 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’ll be too late. AI is a fundamental risk to the existence of human civilization.”

Meanwhile, Zuckerberg advocates for rapid AI advancement, and he believes that AI can enormous positive impact in the immediate future. In his open letter on “building a global community,” Zuckerberg highlighted several ways Facebook is using AI for social good, including fighting abuse, terrorist propaganda and fake news. In his letter, Zuckerberg said that “discussion around AI has been oversimplified to existential fear-mongering,”

“The harm is that sensationalism moves people away from balanced nuanced opinions towards polarized extremes,” Zuckerberg added. “If this continues and we lose common understanding, then even if we eliminated all misinformation, people would just emphasize different sets of facts to fit their polarized opinions.”

Zuckerberg has yet to respond to Musk’s latest comment.

Photo: Facebook