It’s fascinating to imagine the conversations that happen behind closed doors between the world’s richest and most powerful, so when they occur in the open — and over topics that impact the future of the world — it’s hard to do anything but grab the popcorn and watch intensely.

Billionaire business icon Elon Musk — of Tesla, SpaceX and more fame — just fired back at Mark Zuckerberg over his grasp of the future of AI, claiming that the Facebook CEO’s “understanding of the subject is limited.”

Ouch… but Musk himself has been accused of knowing little about AI, from Rodney Brooks, the founding director of MIT’s Computer Science and Artificial Intelligence Lab. Brooks is also the cofounder of both iRobot and Rethink Robotics.

I've talked to Mark about this. His understanding of the subject is limited. — Elon Musk (@elonmusk) July 25, 2017

He was responding to comments made by Zuckerberg this weekend — he chatted to fans on a Facebook live stream for an hour and a half while grilling meat on his BBQ, no less. The social network supremo had some strong words for AI pessimists (realists?) who believe and argue that care and regulation is needed to safeguard the future of our race before AI becomes mainstream.

Musk is fairly outspoken on this topic. While a proponent of tech and artificial intelligence in particular, he recently called its progress the “biggest risk we face as a civilisation.”

“AI is a rare case where we need to be proactive in regulation instead of reactive because if we’re reactive in AI regulation it’s too late,” he said at a meeting of U.S. governors this year.

AI is increasingly a critical part of the Facebook business, while Zuckerberg himself has tinkered with the tech to develop his own home automation system, so perhaps naturally he feels differently.

“I think people who are naysayers and try to drum up these doomsday scenarios — I just, I don’t understand it. It’s really negative and in some ways I actually think it is pretty irresponsible,” he said, according to Silicon Valley Business Journal.

The publication evidently tuned in for the full 90-minute grill-fest, alongside over four million others.

AI is a multi-faceted and complicated subject. And not one that 140-character tweets or back-garden live streams are best suited for explaining. This back-and-forth between two of the world’s most influential figures in business will at least help bring this topic to the fore, and encourage deeper discussions around the future of AI.

Zuckerberg and Musk have been involved in drama before. Last year, a Facebook satellite was destroyed when the SpaceX rocket carrying it exploded on launch in Florida. The satellite was part of Facebook’s Internet.org global connectivity program.