SAN FRANCISCO – Elon Musk and Mark Zuckerberg have clashed on artificial intelligence, space travel and the direction of technology.

On Friday, Musk showed just how little love lost there was between the two tech titans.

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Musk, the chief executive of SpaceX and Tesla, deleted the Facebook pages of both of his companies. In doing so, he joined a growing chorus of tech leaders calling for people to abandon Zuckerberg’s social network after it allowed a political consulting firm, Cambridge Analytica, to obtain and misuse data on 50 million users. The revelations have plunged Facebook into its worse public relations crisis in years.

As with most news in 2018, Musk’s decision started with a barrage of tweets.

The tech luminary began by criticizing Sonos, a maker of wireless speakers, which had pulled some ads from Facebook for a week.

“Wow, a whole week. Risky …,” Musk tweeted in response to a news article about Sonos’ move.

A minute later, he replied to Brian Acton, the founder of WhatsApp, which Facebook had acquired for $19 billion several years ago. Acton, who has since left Facebook, had on Wednesday called for people to “#deletefacebook.”

“What’s Facebook?” Musk replied to Acton. Then Musk announced he would shut down the SpaceX and Tesla pages. He said the Tesla Facebook page “looks lame anyway.”

The posts, which sent the Twittersphere into a virtual frenzy, escalated a public feud between Musk and Zuckerberg. Musk has often urged people to be cautious of embracing technology such as artificial intelligence because of the consequences it might bring, once saying it could become so powerful it would start wars and turn people into its “house cats.”

Zuckerberg has argued that people need to trust and embrace technology in their lives. When the Facebook chief executive was asked about Musk’s warnings around artificial intelligence during a Facebook Live broadcast in 2017, he called Musk a “naysayer.” That’s an insult in a technology world that celebrates perpetual optimism.

“With AI especially, I’m really optimistic,” Zuckerberg said. “People who are naysayers and kind of try to drum up these doomsday scenarios — I just, I don’t understand it. I think it’s really negative and in some ways I actually think it is pretty irresponsible.”

In response, Musk shot back that Zuckerberg did not fully comprehend the issues.

“I’ve talked to Mark about this,” Musk wrote. “His understanding of the subject is limited.”

The two have also clashed on space travel. Zuckerberg traveled to Kenya in 2016 for the launch of a Facebook-affiliated satellite called Amos-6, which was set to go to outer space in a SpaceX rocket. But the rocket exploded. Zuckerberg released a chilly statement.

“As I’m here in Africa, I’m deeply disappointed to hear that SpaceX’s launch failure destroyed our satellite that would have provided connectivity to so many entrepreneurs and everyone else across the continent,” he wrote on Facebook.

Musk is a frequent Twitter presence, who has posted increasingly macho and humor-focused messages including video of himself playing with a flamethrower.

He said he plans to keep using his Instagram account, which is owned by Facebook, and on which he has 6.9 million followers.

When one reporter said on Twitter that it was remarkable Musk had so much time to troll online, Musk wrote, “What, a troll, me!?”

Facebook and SpaceX didn’t immediately have a comment on Musk’s deleted pages. A Tesla spokeswoman did not have a comment beyond Musk’s tweets.