Elon Musk took another shot at Peter Navarro on Tuesday over tariffs, calling President Donald Trump’s top adviser on trade and manufacturing a “moron” and “dumber than a sack of bricks.”

Musk, a senior Trump adviser who had promoted Trump’s agenda, has been critical of Navarro, one of the architects of Trump’s tariff policy who has made the rounds in media defending the sweeping tariffs the president imposed last week that sent world markets plunging.

Musk’s insults Tuesday came after Navarro called the Tesla CEO a “car assembler” rather than a “manufacturer,” claiming that key components of his Teslas come from overseas.

That prompted Musk to respond.

“Navarro is truly a moron. What he says here is demonstrably false,” he posted on X.

He claimed in a second post, “Tesla has the most American-made cars. Navarro is dumber than a sack of bricks,” and tagged Navarro’s handle in the post.

Asked about the feud at Tuesday’s White House press briefing, press secretary Karoline Leavitt dismissed it as “boys will be boys.”

“No, look, these are obviously two individuals who have very different views on trade and on tariffs. Boys will be boys, and we will let their public sparring continue,” Leavitt said. “And you guys should all be very grateful that we have the most transparent administration in history.”

Musk threw shade at Navarro early Saturday morning over his Harvard education.

After a social media user posted a clip defending Navarro’s explanation of the White House’s tariffs, pointing out his PhD in economics from Harvard, Musk responded, “A PhD in Econ from Harvard is a bad thing, not a good thing. Results in the ego/brains>>1 problem.”

In an interview on Fox News Channel’s “Sunday Morning Futures,” Navarro responded to Musk’s posts, saying, “Elon, when he’s in his DOGE lane, is great, but we understand what’s going on here. Elon sells cars. He’s simply protecting his own interests.”

“There’s no rift here,” he added. “Look, Elon, he’s got X, he’s got a big microphone. We don’t mind him saying whatever he wants. But, just, the American people need to understand that we understand what that’s all about, and it’s fine.”

Musk said he offered Trump advice on tariffs when he spoke via live stream in Washington to the Italy’s League Congress Conference in Florence on Saturday.

Musk expressed his hope for the U.S. and Europe to create “a very close, stronger partnership” and reach a “zero-tariff” policy soon.

“I hope it is agreed that both Europe and the United States should move, ideally, in my view, to a zero-tariff situation, effectively creating a free trade zone between Europe and North America,” Musk said.

“And also more freedom of people to move between Europe and North America if they wish, if they wish to work in Europe or wish to work in America, they should be allowed to do so, in my view. So that has certainly been my advice to the president,” he continued.