Elon Musk on Tuesday launched a blistering social media tirade against White House trade adviser Peter Navarro, calling him “a moron” over comments made about Tesla’s manufacturing practices, an extraordinary public display of hostility from one top administration adviser against another.

Navarro, speaking on CNBC on Monday, claimed that Musk “isn’t a car manufacturer — he’s a car assembler,” arguing that Tesla relies heavily on foreign supply chains, including batteries from Japan and China. “What we want … is tires made in Akron, [Ohio,] transmissions in Indianapolis, [Indiana] and engines in Flint, [Michigan].”

Musk, a senior administration adviser, fired back Tuesday morning in a rapid-fire tweetstorm. “Navarro is truly a moron. What he says here is demonstrably false,” Musk wrote in a post on his social media site, X.

The spat comes amid worldwide blowback of President Donald Trump’s tariffs, including three days of stock market volatility and questions about whether the administration is going to scale them back via deals with foreign leaders.

The rift between Musk and Navarro, which has been slowly simmering in recent days, provides a window into possible infighting between the people closest to the president.

On X, Musk went on to try to prove his point.

“Tesla has the most American-made cars. Navarro is dumber than a sack of bricks,” he added, linking to an industry index ranking Tesla’s models Y, 3, X, and S as the top four most American vehicles based on assembly location, parts content, engine origin, transmission origin and U.S. manufacturing workforce.

In a third post, Musk wrote: “By any definition whatsoever, Tesla is the most vertically integrated auto manufacturer in America.”

He concluded with a jab referencing Navarro’s 2011 book “Death By China,” which included a fictional trade expert named “Ron Vara” — an anagram of Navarro.

“Navarro should ask the fake expert he invented, Ron Vara.”