In a post on X, Altman said: “Watching @potus more carefully recently has really changed my perspective on him. I wish I had done more of my own thinking and definitely fell in the npc [non-playable character] trap. I’m not going to agree with him on everything, but I think he will be incredible for the country in many ways!”

The comments came amid a flurry of online exchanges between Musk, Altman, and Microsoft over the $500 billion Stargate Project announced by Trump on Tuesday.

Musk kicked off the debate by accusing OpenAI and SoftBank of not having the money for the ambitious AI infrastructure project. The billionaire said in a post on X he had it on “good authority” that SoftBank “has well under $10B secured.”

OpenAI has said the joint venture will invest an initial $100 billion of private capital to fund the U.S. AI infrastructure, with a further $400 billion expected over the next four years, but Musk isn’t the only one to question the project’s eye-watering finances.

Some have pointed to SoftBank’s most recent public finances as a potential problem.

Earlier this year, SoftBank Group only had $30 billion in cash—a far cry from the $100 billion promised. Masayoshi Son’s firm has also taken a reputational hit from a few bad bets, most notably its backing of bankrupt co-working firm WeWork.

Altman and Microsoft CEO Satya Nadella have attempted to silence some of the questions surrounding the project’s funding. The OpenAI chief responded to Musk’s comment, saying he was “wrong as you surely know.”

“This is great for the country,” Altman continued. “I realize what is great for the country isn’t always what’s optimal for your companies, but in your new role I hope you’ll mostly put [the U.S.] first.”

In response to a later post, Altman upped the ante, saying that while he respected Musk’s ambition, he didn’t think the Tesla CEO was a nice person or treating OpenAI fairly.

Musk lobbed a series of posts back at the OpenAI chief, bringing up old anti-Trump tweets, slamming him for his connection with Democrat donor Reid Hoffman, reigniting an ongoing feud over OpenAI’s profit structure—in which he called Altman a “liar”—and criticizing OpenAI’s partnership with media outlet Axios.

Microsoft’s Nadella also waded into the debate over the Stargate Project’s funding, telling CNBC he was “good” for his $80 billion contribution.

The Microsoft CEO also replied to a post from Musk on X, saying: “And all this money is not about hyping AI, but about building useful things for the real world!”

Musk and Altman are old rivals

It’s not the first time Altman and Musk have publicly sparred with each other online.

The pair have a history that goes back to OpenAI’s early days.

Altman and Musk, along with nine others, were cofounders of the AI lab and worked together at the company until Musk stepped down from the board of directors in early 2018.

Altman and other OpenAI executives claim Musk had been trying to merge OpenAI with Tesla, but when this was unsuccessful, he chose to leave to build an AGI competitor within Tesla.

In response, Musk has railed against OpenAI’s corporate structure, accusing the company of abandoning its nonprofit roots for the sake of its multibillion-dollar partnership with Microsoft.

Representatives for Musk and Altman did not immediately respond to a request for comment from Fortune.