In an apparent tit-for-tat move, China said on December 3 that it would ban the export of several rare minerals to the U.S., a day after the Biden administration tightened Chinese access to advanced American technology.

The New York Times said the bans are an escalation of the tech war between the world’s two biggest powers, and signal Beijing’s willingness to engage in supply chain warfare. 

The bans cover sales to the U.S. of gallium, germanium, antimony and so-called superhard materials  used to make valuable products, such as weaponry and semiconductors, on the grounds that they have dual military and civilian uses, China’s Ministry of Commerce said. The export of graphite would also be subject to stricter review.

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The U.S. Commerce Department announced December 2 it will expand the list of 140 companies included in the so-called “entity list,” and would limit exports of high-bandwidth memory chips to China, which are needed to process massive amounts of data in advanced applications such as artificial intelligence. China’s Commerce Ministry at that time protested and said it would act to protect its “rights and interests.”