Elon Musk slammed President Trump’s top trade adviser as “dumber than a sack of bricks” on Tuesday, exposing a remarkable rift in the president’s inner circle over the wide-ranging tariffs that have upended the global economy.
The feud between Mr. Musk and Peter Navarro, who has been the architect of many of Mr. Trump’s trade plans, has been simmering for days as the administration’s new tariffs have caused huge losses across global financial markets.
So far, Mr. Trump has not weighed in on the clash between his top aides, both of whom he claims to hold in high regard. But Mr. Musk’s words — though aimed at Mr. Navarro — were a rare criticism of Mr. Trump’s policies from one of his most influential advisers.
Mr. Musk, the world’s richest man, is estimated to have lost roughly $31 billion since Mr. Trump announced sweeping tariffs on foreign countries on April 2, according to the Bloomberg Billionaires Index.
The squabble escalated on Monday when Mr. Navarro said on CNBC that Mr. Musk was not a “car manufacturer” but a “car assembler” because Tesla, Mr. Musk’s electric vehicle company, relied on parts from around the world.
Mr. Musk fired back on Tuesday, calling Mr. Navarro a “moron” and “dumber than a sack of bricks” in a post on X, the social media site he owns. Later in the day, Mr. Musk doubled down, posting that he wanted to “apologize to bricks.”
“That was so unfair to bricks,” Mr. Musk wrote. He also used a slur to refer to Mr. Navarro, calling him “Peter Retarrdo.”
Karoline Leavitt, the White House press secretary, tried to downplay the feud.
“Boys will be boys, and we will let their public sparring continue,” she told reporters.
Mr. Navarro ignored questions from reporters at the White House on Tuesday afternoon about Mr. Musk’s posts on social media.
Mr. Trump has long allowed, and at times fostered, conflict between his top advisers, but it is unusual for animus between aides to play out so publicly. Mr. Navarro was a senior official on trade issues during Mr. Trump’s first term and stayed loyal to the president afterward, even spending four months in jail after being convicted of contempt of Congress for refusing to testify in its investigation into the Jan. 6, 2021, attack on the Capitol.
Mr. Musk, a key member of the president’s inner circle who spent hundreds of millions of dollars to support his presidential campaign, is usually a staunch supporter of Mr. Trump’s policies. But the tariffs have been an exception.
Mr. Musk has rejected Mr. Trump’s approach and called for “zero tariffs” between the United States and Europe. He has chastised Mr. Navarro for having a Ph.D. in economics from Harvard, writing that was “a bad thing, not a good thing,” and then posting that Mr. Navarro “ain’t built” anything, using an expletive. (He later deleted the second post.)
Mr. Musk’s brother, Kimbal, has also critiqued the tariffs, posting a flurry of messages on X over the last several days and defending his brother. He asserted that the president had “implemented a structural, permanent tax on the American consumer.”
Mr. Musk often uses his X account to barrage his critics, insulting them and inciting his nearly 219 million followers to join in. Since acquiring Twitter and renaming it X, Mr. Musk has often targeted judges who have made rulings about his companies that he disagrees with. And in recent months, Mr. Musk lashed out at judges who have slowed or halted his federal cost-cutting efforts at the Department of Government Efficiency.
Since Mr. Trump announced the tariffs last week, administration officials have given varying and, at times, conflicting explanations in public about the president’s plan. Mr. Navarro has been adamant: The tariffs are not a negotiating tactic to win more favorable trade deals with other countries. But Treasury Secretary Scott Bessent has signaled that Mr. Trump is open to negotiations as countries flood the White House with calls to discuss new deals.
“President Trump, as you know, is better than anyone at giving himself maximum leverage,” Mr. Bessent said on Fox News.
Kate Conger and Maggie Haberman contributed reporting.