Billionaire Elon Musk escalated his attacks against White House trade adviser Peter Navarro Tuesday, calling him a “moron” and “dumber than a sack of bricks.”

Elon Musk called Donald Trump’s top trade adviser Peter Navarro “dumber than a sack of bricks” Tuesday, once again betraying the administration’s deep rift over the president’s disastrous tariffs. Navarro found himself in hot water with Musk after he called the billionaire bureaucrat a “car assembler” during an appearance on CNBC Monday.