Tesla CEO Elon Musk is also the CEO of SpaceX.
SpaceX

SAN FRANCISCO — Elon Musk took to his favorite soapbox Thursday to press President Trump, another Twitter-holic, on China's restrictive auto trade policies.

Responding to a Trump tweet from Wednesday that said China had been asked to propose ways to reduce its deficit with the U.S. by $1 billion, the Tesla and SpaceX CEO posed a rhetorical question that suggested Tesla's growth in China was being held back by unfair trade practices.

"Do you think the US & China should have equal & fair rules for cars? Meaning, same import duties, ownership constraints & other factors," Musk tweeted.

He then added a second message for @realDonaldTrump, noting that every American car going to China pays a 25% import duty, "but a Chinese car coming to the US only pays 2.5%, a tenfold difference."

Finally, Musk capped his mini-tweetstorm lamenting that "no US auto company is allowed to own even 50% of their own factory in China, but there are five 100% China-owned EV auto companies in the US."

Musk was referring to a variety of automotive ventures, many of them focused on futuristic electric vehicles with self-driving capabilities, which have taken root largely in California backed by Chinese billionaires. 

These include Faraday Future and Nio, which so far have been long on sizzling prototype previews and short on actually getting a production model underway.

Faraday Future announced last fall that it had found a production facility in California, but there has been little word from the company since. Reports indicate that Nio is looking to raise $2 billion in an upcoming public stock offering. 

This image from video provided by SpaceX shows the company's spacesuit in Elon Musk's red Tesla sports car which was launched into space.
SpaceX via AP

After a slow start in China, Tesla saw revenues double to $2 billion in 2017, according to an Electrek report.

The growth stemmed in part from the company's build-out of its Supercharger network as well as Chinese consumers' interest in electric vehicles as a hedge against mounting air pollution problems.

But, in order to truly take advantage of the Chinese market, Musk has to sell buyers there on his first entry-level vehicle, the Model 3, whose production has been well behind a promised pace of around 500,000 cars a year.

Model 3.
Tesla

For true volume sales at the highest profit margin, Musk would have to build a Tesla plant in China so he doesn't have to rely on shipping products from California, which incur import duties that are passed along to Chinese consumers. Musk has been in talks with Shanghai officials to build a factory in the city's free trade zone.

Musk's tweeted comments about China auto trade practices have yet to draw a response from Trump.

More: We rented a Tesla Model 3 from a new owner: Call it spartan, high-tech and compelling

More: Hyundai taunts Tesla CEO Elon Musk in ad for electric SUV

But during a televised meeting Thursday, Trump commented on the nation's privately funded space programs. He made a pointed nod toward the launch last month of Musk's SpaceX Falcon Heavy rockets, whose boosters returned to launch pads in order to be reused.

"These rich guys, they love rocket ships ... that's good, that's better than us paying for them," Trump said. "I don't know if you saw with Elon, the rocket boosters where they're coming down, what's more amazing than seeing the rocket go up ... they landed so beautifully. But we're bringing that whole space flight back. We'll be sending something beautiful to Mars in the near future."

Musk has set his sights on a manned mission to Mars.

Follow USA TODAY transportation tech writer Marco della Cava on Twitter.