Elon Musk has cast doubt on Donald Trump’s $500 billion AI project by questioning whether it has enough financial backing. “They don’t actually have the money,” the MAGA billionaire wrote on X in a rare public dig at Trump just hours after the president made a big announcement about the privately funded initiative.

U.S. President Donald Trump on Thursday dismissed criticism from close ally Elon Musk about a $500 billion artificial intelligence project that Trump announced with great fanfare at the White House earlier this week.

Altman and Musk were OpenAI’s founding co-chairs in 2015, but their relationship has devolved into name-calling and lawsuits.