WASHINGTON, United States (AFP) — Additional US tariffs on Chinese imports are set to reach 104 per cent on Wednesday, the White House told AFP, as Washington doubles down on planned action after Beijing vowed a “fight to the end” on levies.

US President Donald Trump had vowed a further 50 per cent tariff on goods from China if Beijing did not retract upcoming retaliation — and the White House confirmed that Trump will proceed with this action, taking the overall added duties this year to 104 per cent.

Meanwhile billionaire Elon Musk blasted President Donald Trump’s senior trade advisor Peter Navarro as “truly a moron” and “dumber than a sack of bricks” on Tuesday in a growing rift over the US tariff policy that has rocked the world.

The extraordinary public spat came after Navarro described the Tesla boss and so-called Department of Government Efficiency (DOGE) chief as “not a car manufacturer” but “a car assembler” who relies on imported parts.

Musk, the world’s richest person, has previously signalled his opposition to the president’s new import tariffs that have roiled markets.

“Navarro is truly a moron. What he says here is demonstrably false,” Musk posted on his X social network, under a clip of Navarro saying Tesla imported batteries, electronics and tires, and that Musk “wants the cheap foreign parts.”

Musk doubled down in a series of other messages, saying that “Tesla has the most American-made cars. Navarro is dumber than a sack of bricks.”

Musk also dubbed him “Peter Retarrdo” and said Navarro “should ask the fake expert he invented, Ron Vara” – referring to a fictional pundit Navarro quoted in a series of books and a policy memo, using an anagram of his own name.

The White House played down the row.

“Boys will be boys and we will let their public sparring continue,” Press Secretary Karoline Leavitt told a briefing when asked if the spat would harm the White House’s messaging on tariffs.

The South African-born tycoon recently backed the idea of a free-trade zone between North America and Europe – a wish at odds with Trump’s flagship tariffs.

The US president has ruled out any pause in his aggressive stance despite retaliatory action from China and signs of criticism from within his normally loyal Republican Party.