Elon Musk stepped up a clash of billionaires after expressing skepticism about the finances of the backers of Stargate, an AI infrastructure plan announced on Tuesday by US President Donald Trump and three business executives.

Representatives of Oracle, OpenAI and Japan's SoftBank stood with Trump at the White House during the announcement. Their companies will invest $100 billion in total for the project to start, with plans to eventually put up to $500 billion into Stargate, CNN reported.

But just before midnight on Tuesday, Musk wrote on his social media platform X.com, where he has nearly 214 million followers, "They don't actually have the money."

Early Wednesday morning, he added: "SoftBank has well under $10B secured. I have that on good authority."

Billionaire OpenAI CEO Sam Altman replied on Wednesday to Musk's comments, writing on X, "wrong, as you surely know. want to come visit the first site already under way? this is great for the country. 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 (America) first."

The two men have traded barbs in the past. Musk, who has sued Altman, called him a "swindler" and "someone who is not trustworthy", while Altman has accused Musk of "clearly being a bully".

While Stargate plans to bring on more investors, the three main partners have restrictions on their cash, The Wall Street Journal reported.

OpenAI raised nearly $7 billion in October but is losing money. Oracle has about $11 billion in cash and marketable securities but more in debt, while SoftBank has about $30 billion of cash handy, the Journal reported.

In December, SoftBank CEO Masayoshi Son committed to invest at least $100 billion in American projects over the next four years, at an event at Mar-a-Lago, Trump's resort in Florida.

Son, Altman and Oracle co-founder Larry Ellison attended the Stargate news conference with Trump on Tuesday.

What made the comments noteworthy by Musk, the Tesla CEO, is that the president has picked him to lead the new Department of Government Efficiency, or DOGE as it is called, and he has been a frequent visitor at Mar-a-Lago.

Musk co-founded OpenAI and gave the company its name, but left its board in 2018. He has said it was intended to be open-source software.

"Altman assured Musk that the nonprofit structure guaranteed neutrality and a focus on safety and openness for the benefit of humanity, not shareholder value," the complaint filed in August in US District Court in Northern California said. "But as it turns out, this was all hot-air philanthropy — the hook for Altman's long con."

Musk filed a similar lawsuit against OpenAI in March 2024, claiming that it had not followed its founding agreement by emphasizing "profit over the technology's potential benefit to humanity", the Journal reported. But Musk withdrew the complaint in June.

Musk also has claimed that ChatGPT, a generative artificial intelligence chatbot developed by OpenAI, has abandoned its original nonprofit mission by keeping some of its most advanced AI technology for private customers, CNN reported.

Karoline Leavitt, the White House press secretary, told Fox News that "the American people should take President Trump and those CEOs' words for it".

Musk, the world's richest man, whose companies also include SpaceX, which owns Starlink, a satellite internet constellation, last year started his own AI company, xAI, which is building a data center in Memphis, Tennessee.

Musk says xAI faces unfair competition from OpenAI and its business partner Microsoft, which has supplied the massive computing resources needed to build AI systems such as ChatGPT.

Forbes reported that UBS analyst Karl Keirstead, in a note to clients on Wednesday, wrote, "OpenAI is in a race against Elon Musk-backed xAI, Google, Meta and Anthropic (funded by Amazon) among others" and "this puts OpenAI in a better position long-term to win the model war."

Of Musk's comments about Stargate's financing, Satya Nadella, CEO of Microsoft, said on CNBC on Wednesday, "All I know is, I'm good for my $80 billion."

Shares of Oracle and Microsoft rose 6.8 percent and 4.1 percent, respectively, in Nasdaq Stock Market trading on Wednesday.

Trump said Tuesday that Stargate would create 100,000 jobs and would counter China by helping keep "the future of technology" in the US.

"This will include the construction of colossal data centers, massive structures," he said. "These buildings, big, beautiful buildings, are going to employ a lot of people."

The Information, a tech news website, first reported on an OpenAI data center project called Stargate in March 2024, suggesting that it's been in the works almost a year before Trump announced it.

Another company — Crusoe Energy Systems — announced in July that it was building a large and "specially designed AI data center" outside Abilene, Texas, at a site run by energy technology company Lancium.

Crusoe and Lancium said in a joint statement at the time that the project was "supported by a multibillion-dollar investment" but didn't disclose its backers.

Agencies contributed to this story.

hengweili@chinadailyusa.com