The venture, called Stargate, "will invest $500 billion, at least, in AI infrastructure in the United States," Trump said in remarks at the White House.

"This monumental undertaking is a resounding declaration of confidence in America's potential," he said, a day after his swearing in for a second term.

OpenAI's chief executive Sam Altman, SoftBank's chief Masayoshi Son and Oracle founder Larry Ellison attended the announcement.

Their project is committed to invest an initial $100 billion and up to $500 billion over the next four years in the project, according to Son.

The venture comes as big tech players are scrambling to meet AI's voracious computing needs, as well as find the electric power necessary to expand the new technology.

Trump said Stargate will be building the physical and virtual infrastructure to power the next generation of advancements in AI, including the construction of "colossal data centers."

OpenAI later said in an X post that the project "will not only support the re-industrialization of the United States but also provide a strategic capability to protect the national security of America and its allies."

It added that SoftBank and OpenAI were the lead partners for Stargate, with SoftBank having financial responsibility and OpenAI having operational responsibility.

The post also said that MGX, a technology fund from the United Arab Emirates, was a fourth investor, while "Arm, Microsoft, NVIDIA, Oracle, and OpenAI are the key initial technology partners."

"Buildout is currently underway, starting in Texas, and we are evaluating potential sites across the country for more campuses as we finalize definitive agreements," it added.

Texas is fast becoming an alternative to California for US big tech investments.

In turn, the three bosses thanked Trump.

"We couldn't have done this without you," said Altman.

Ellison, in brief remarks at the White House, underlined the medical innovations promised by AI such as "early cancer detection with a blood test."

SoftBank shares soared more than eight percent in Tokyo after the announcement.

News of the project comes a day after Trump's inauguration ceremony was attended by prominent tech chiefs, including Apple CEO Tim Cook, Google CEO Sundar Pichai, Meta CEO Mark Zuckerberg and Amazon leader Jeff Bezos.

Later on Monday, Trump rescinded an executive order from his predecessor Joe Biden that established oversight measures for companies developing powerful AI models.

Its repeal leaves the United States, home to most of the world's most impactful AI technology, without nationwide AI development guidelines, even if individual states are pursuing their own measures.