Elon Musk on Tuesday described Peter Navarro, a senior White House trade advisor, as "truly a moron" and "dumber than a sack of bricks" in a growing rift over Donald Trump's tariff policy.

Musk, a key aide to the president, has signaled opposition to the tariffs, and the Tesla CEO hit out after Navarro described him as "not a car manufacturer" but "a car assembler."