Sam Altman is done playing nice with Elon Musk

• OpenAI execs have published their response to a lawsuit from Elon Musk.
• The blogpost made public a series of internal emails between Musk and OpenAI execs.

When it comes to OpenAI, Elon Musk is not afraid to go for the jugular. But Sam Altman has made clear that he's going to fight back — in his own way.

On Tuesday, OpenAI executives, including Altman, Greg Brockman, and Ilya Sutskever, published a series of private internal emails between Musk and OpenAI executives dating from between 2015 and 2018.

The emails were referenced in a company blog post responding to Musk's lawsuit against OpenAI. It's the latest sign of the increasingly toxic relationship between Altman and Musk.

Musk, who left OpenAI in 2018, accused the AI company of abandoning its founding principles amid a multibillion-dollar partnership with Microsoft in the lawsuit filed Friday. The suit argued that the company's transition to a "capped-profit" division breached its original nonprofit contract.

The OpenAI execs published the post to announce their plans to move to dismiss the lawsuit and share "some facts about our relationship with Elon."

They wrote: "We're sad that it's come to this with someone whom we've deeply admired — someone who inspired us to aim higher, then told us we would fail, started a competitor, and then sued us when we started making meaningful progress towards OpenAI's mission without him."

Altman and OpenAI execs have largely tried to avoid publicly confronting the Tesla CEO.

Last year, amid a flood of public attacks from Musk, Altman described the billionaire as one of his heroes in an interview with Lex Fridman and said he was empathic to Musk's concerns about AI safety.

Altman reportedly dealt with Musk in private shortly after the billionaire announced he had severed OpenAI's access to X's data. Following the move, Altman invited Musk to OpenAI's headquarters for a closed-door meeting that lasted hours, The Wall Street Journal reported.

On the occasions where Altman has criticized Musk, he's tended to take a more tempered approach. For example, in an interview with journalist Kara Swisher, Altman called Musk a "jerk" before adding that the billionaire "really does care" about AI safety.

Musk has continued to lob many public criticisms at the AI lab he helped build, firing shots at its flagship product, ChatGPT, and critiquing its lucrative partnership with Microsoft.

For the most part, Altman seems to be done playing nice. He addressed his personal relationship with Musk directly in a memo sent to employees shortly after the lawsuit was filed.

"On a personal level it's sad," Altman said in the memo, which was reported on by the Journal. Though he said he'd considered Musk a personal hero, he expressed disappointment that Musk wasn't on OpenAI's side.

"I like to think of Elon as a builder and someone who competes by attempting to build better technology, and someone who I'd hope to be on our side," he said. "I miss the old Elon."

Last week, Altman also appeared to troll the billionaire by dredging up an old Twitter exchange with Musk.

Musk and Altman naturally have differing opinions on their soured partnership.

The Journal reported cited people close to Musk, who said Musk was jealous of OpenAI's success in the AI race. However, others said Musk is genuinely worried about AI safety and the future of humanity, the report said.

Representatives for Musk and Altman did not immediately respond to a request for comment from Business Insider, made outside normal working hours.