Billionaire CEOs Mark Zuckerberg and Elon Musk are trading jabs online over the future of artificial intelligence.

In a Facebook Live broadcast from his backyard on Sunday, Zuckerberg, the social media network鈥檚 CEO, suggested that Musk is 鈥渋rresponsible鈥� for highlighting the dangers of AI.

Musk, the entrepreneur behind SpaceX and Tesla Inc., responded on Twitter by saying that Zuckerberg鈥檚 鈥渦nderstanding of the subject is limited.鈥�

In what started out as a in his backyard, chatting about grilling and Sunday family rituals, he fielded questions from viewers on various topics, including philanthropy and the evolution of technology.

One viewer wrote that he recently watched an interview in which Elon Musk said that AI was his biggest fear for the future. The viewer asked Zuckerberg for his thoughts on AI.

鈥淚 have pretty strong opinions on this. I鈥檓 really optimistic,鈥� Zuckerberg replied. 鈥淚 think you can build things and the world gets better. With AI especially, I鈥檓 really optimistic. I think that people who are naysayers and kind of try to drum up these doomsday scenarios鈥 don鈥檛 understand it. It鈥檚 really negative and in some ways I actually think it鈥檚 pretty irresponsible.鈥�

In response to an article about Zuckerberg鈥檚 comments, Musk tweeted: 鈥淚鈥檝e talked to Mark about this. His understanding of the subject is limited.鈥�

When someone on Twitter told Musk that he should argue his case in 鈥渁 well written blog piece,鈥� he responded with: 鈥淢ovie on the subject coming soon,鈥� without elaborating.

Even though Musk鈥檚 company Tesla is at the forefront of autonomous driving technology, he has issued multiple dire warnings about artificial intelligence in the past. More recently, he said AI poses 鈥渁 fundamental risk to the existence of human civilization.鈥�

Zuckerberg said on Sunday that he strongly believes AI will improve and save human lives in the future, especially when it comes to health-care technology and self-driving cars.