Stand back everyone, tech billionaires Mark Zuckerberg and Elon Musk are having a social media spat about artificial intelligence.

First, and for quite some time now, Musk aired his concerns about artificial intelligence (AI) and how it could potentially start thinking for itself, rise up against us and exterminate the human race.

Then Zuckerberg, during one of his Facebook question-and-answer sessions (which, he claims, are nothing to do with a 2020 presidential bid) said he had some "pretty strong opinions" on Musk's fear of AI.

The Facebook boss went on: "I think you can build things and the world gets better, and with AI especially, I'm really optimistic. I think people who are naysayers and try to drum up these doomsday scenarios are...I just, I don't understand it. It's really negative and in some ways I think it is pretty irresponsible."

Zuckerberg goes on to discuss how advances in AI could potentially lead to "so many improvements in the quality of our lives". Then, parking driverless tanks right on Tesla boss Musk's lawn, Zuckerberg says: "If you're arguing against AI you're arguing against safer cars that aren't going to have accidents."

Two days later, Zuckerberg's comments are said to "blast" Musk's warnings by Twitter user Darren Cunningham, who tags Musk's handle in his tweet. Musk replies: "I've talked to Mark about this. His understanding of the subject is limited."

Shots fired.

Finally, Musk is asked in a tweet by a mechanical engineer to support his AI concerns via a blog post. He replies: "Movie on the subject coming soon...," which some of his followers claim is a reference to Blade Runner 2049.