Although Altman admits his cofounder “did a lot to help OpenAI in the early days,” he told the Free Press in an interview published Thursday that Musk is “also clearly a bully, and he’s also someone who clearly likes to get in fights.”

OpenAI did not immediately respond to Fortune’s request for additional comment.

The overarching battle between these two billionaires stems from a fundamental disagreement over OpenAI’s company structure and control. Musk has on several occasions sued OpenAI, alleging the nonprofit he helped found cannot legally convert to a corporation without violating its original purpose: to benefit humanity as a whole by developing the world’s first artificial general intelligence (AGI).

However, OpenAI alleges Musk had long pushed for OpenAI to become a for-profit company. Musk also reportedly wanted OpenAI to become part of Tesla, which the company saw as a conflict of interest as the electric car company started increasingly using AI technologies in its products. 

“His own words and actions speak for themselves—in 2017 Elon not only wanted, but actually created, a for-profit as OpenAI’s proposed new structure,” according to an open letter published by OpenAI on Dec. 13, which includes screenshots, other documents, and a timeline of events involving Musk since 2015. “When he didn’t get majority equity and full control, he walked away [in 2018] and told us we would fail.”

Representatives of Musk through X and Tesla did not immediately respond to Fortune’s requests for comment.

OpenAI has since shifted to a split corporate structure, adding a for-profit arm in 2019 with a $1 billion investment from Microsoft. The goal of the partnership was to “democratize AI,” Microsoft CEO Satya Nadella said at the time.

Amid the four lawsuits filed by Musk against OpenAI, there has been an extensive battle on social media. But Altman calls that “a little bit of a sideshow.” And instead of humoring Musk on X, Altman says OpenAI ignores a lot of what he says.

“We do not sit there and throw tomatoes back and forth on Twitter,” Altman told the Free Press. “The right thing for us to do is just keep doing incredible research.”

Musk has even gone so far as to allege, in one of his lawsuits against OpenAI, that Altman and Greg Brockman, another cofounder, “manipulated” him to help create the company. The lawsuit alleges Altman and others “intentionally courted and deceived Musk, preying on Musk’s humanitarian concern about the existential dangers posed by artificial intelligence.”

But despite all of the allegations and drama, Altman is seemingly brushing off Musk’s incessant posts on X and other criticisms about OpenAI, mostly because he’s not the first person Musk has regularly fought with.

“Right now, it’s me. It’s been Bezos, Gates, Zuckerberg, lots of other people,” Altman said in the interview. “And I think, fundamentally, this is about OpenAI doing really well. Elon cares about doing really well.” Currently, OpenAI is valued at $157 billion.

Meanwhile, Musk has launched his own AI startup, xAI, which is training its own large language model on X data. The value of xAI has more than doubled to $50 billion since it last raised money in May.

Despite the feud between Altman and Musk, Altman said he doesn’t think Musk will abuse his position by punishing OpenAI even though he’s become very close with President-elect Donald Trump, making him even more powerful than before.

“I think there are people who will really be a jerk on Twitter, who will still not abuse the system of a country they’re now in a sort of extremely influential political role for,” Altman said during the interview. “That seems completely different to me.”