The court battles over tariffs got all the attention this week but that wasn't the only sign the Trump administration is still engaged in a trade war with China. On Wednesday the administration suspended the sale of jet engines and some high tech chips and software as well. The target of these new restrictions seems to be China's first passenger jet, the C919.

The Trump administration has suspended some sales to China of critical U.S. technologies, including those related to jet engines, semiconductors and certain chemicals and machinery. The move is a response to China’s recent restrictions on exports of critical minerals to the United States, a decision by Beijing that has threatened to cripple U.S. company supply chains, according to two people familiar with the matter.

The new limits are pushing the world’s largest economies a step closer toward supply chain warfare, as Washington and Beijing try to flex their power over essential economic components in an attempt to gain the upper hand in an intensifying trade conflict...

One person familiar with the matter, who declined to be named to discuss private conversations, said the Commerce Department had suspended some licenses that allowed American companies to sell products and technology to COMAC, a Chinese state-owned aerospace manufacturer, for use in its C919 aircraft.

In a companion piece we learn that the C919 is essentially a US/European built airliner which was built in partnership in China starting back when we still had hopes China might become an ally rather than an enemy.

In 2008, China established the state-owned Commercial Aircraft Corporation of China, or COMAC, with the goal of putting a single-aisle commercial jet into service by 2016.

Development of the plane has been slow. The company, which occupies a large expanse of newly built hangars and design studios in Shanghai, suffered delays despite extensive assistance from American and European companies. Its plane, the C919, did not go into commercial service until 2023.

Still, Beijing takes great pride in the C919. State media describes it as one of the country’s “pillars of a great power” with “technology to help civil aviation development and achieve military-civilian integration.”...

Some in Washington now contend that COMAC’s joint ventures facilitate the theft of industrial secrets and undermine American national security. “Almost the entire makeup of the C919 is stolen technology from numerous aviation and technology industries from around the world,” said William R. Evanina, a former director of the United States National Counterintelligence and Security Center, in congressional testimony in 2023.

It's not exactly correct to say all of the tech was stolen. Some of it was just bought from US companies that were happy to sell for the right price.

Less than two years after COMAC was founded, when the C919 was still a distant dream, General Electric agreed to a partnership with the Aviation Industry Corporation of China, or AVIC, a leading Chinese defense contractor. General Electric shared its most advanced commercial avionics with AVIC for the C919, the same state-of-the-art system it had just developed for Boeing’s 787 Dreamliner jet.

General Electric and AVIC worked together on equipping the C919 with an advanced computer core processing system. AVIC has also developed China’s most advanced bombers and its latest stealth fighter jets.

So far, you can only fly the C919 in China or Hong Kong. No where else has approved it yet. But China is trying to ramp up production even as Trump is pulling back. Some commentary in the South China Morning Post was predictably bullish about China's ability to overcome this new hurdle.

Washington’s technology-export restrictions targeting Chinese plane makers this week will delay China’s jet engine indigenisation process in the near term, but any setback will only harden resolve in Beijing for tech self-reliance to test and launch a home-grown engine, analysts said on Friday...

At a Communist Party plenum in 2016, developing advanced home-grown aviation engines was added to a list of crucial science and technology fields prioritised for nationwide investment and research and development, with sights set on breakthroughs by 2030...

Mayur Patel, Asia head at British aviation intelligence firm OAG, said China would need to put up at least US$1 billion for engine research and development and wait two more years to build an engine “from the ground up”.

“China is always looking at home-grown solutions now,” Patel said. “They don’t want to be dependent on foreigners, so they’re going to be sourcing as much as they can locally. It’s one of those things where they will do R&D, and eventually they’ll get there.”

Well, sure. Now that they have a bunch of engines in service which were jointly built for them in American and France, they probably can disassemble them and copy exactly every part given enough time and money. The larger point here is that China continues to beg, borrow or steal every bit of our technology it can (plus leave backdoors in their tech that we buy) and we haven't done a very good job of stopping them. The Trump administration's actions this week are arguably long overdue and probably too late to do more than delay them at this point.