The Chinese government has said it will ban exports of some key semiconductor manufacturing components to the United States, escalating trade tensions, a day after Washington announced restrictions targeting China’s ability to make advanced chips.

Materials banned from export included the metals gallium, antimony and germanium, China’s Commerce Ministry said in a statement, citing concerns over “national security.”

Exports of graphite, another component of semiconductors, would be subject to “more stringent end-use and end-use reviews,” the ministry said. The restrictions step up enforcement of existing curbs on exports of critical minerals that Beijing began imposing last year, but only apply to the U.S. market.

“In order to safeguard national security interests and fulfill international obligations such as non-proliferation, China has decided to strengthen export controls on relevant dual-use items to the United States,” the ministry said.

Gallium and germanium are used in semiconductors, while germanium is also used in infrared technology, fiber optic cables and solar cells. Antimony is used in bullets and other weapons, while graphite is the largest component by volume in electric vehicle batteries.

There are concerns that Beijing could next target other critical minerals, including those with even broader uses such as nickel and cobalt.

China accounts for 94% of global gallium production and 83% of germanium production.

Chinese customs data show there were no shipments of processed or unprocessed germanium or gallium to the U.S. this year through October, when it was the fourth- and fifth-largest market for the minerals a year earlier.

Similarly, China’s total shipments of antimony products fell 97% in October from September after Beijing’s measures limiting its exports took effect.

On Monday, Washington announced sales restrictions on 140 companies, including Chinese chip firms Piotech and SiCarrier, stepping up efforts to curb exports to China of cutting-edge chips that could be used in advanced weapons systems and artificial intelligence.

The new U.S. regulations include controls for two dozen types of chip-making equipment and three types of software tools for semiconductor development or production.

On Tuesday, China said the U.S. had “politicized and weaponized economic, trade and technology issues” as it unveiled its own export restrictions.

The Chinese move also restricts the export of “dual-use items to U.S. military users or for military purposes,” Beijing said.

“The move is clearly a retaliatory strike against the US,” said Dylan Loh, an assistant professor at Nanyang Technological University in Singapore.

“It drives home an important point: China is not completely passive (and) there are some cards it can use to play and beat the U.S. in terms of chips as well.”

These “back and forth restrictions” could lead to supply chain disruptions as well as inflationary pressures if they affect trade for third parties, said Chong Ja Ian, an associate professor of political science at the National University of Singapore.

Brady Wang, deputy director of technology research firm Counterpoint, told AFP that while the metals played a crucial role in high-tech industries, they were upstream in the supply chain, meaning the immediate impact on production was limited . “As trade tensions between the US and China have been ongoing for some time, many intermediate manufacturers in the supply chain have stockpiled these materials.”

Chinese trade associations released similarly worded statements on Tuesday urging their members to look for local alternatives to U.S. chips.

The Internet Society of China urged companies to “be careful when sourcing US chips, expand cooperation with chip companies in other countries and regions, and actively use chips produced and manufactured in China by domestic and foreign companies.”

The China Association of Automobile Manufacturers accused Washington of “arbitrarily changing the control rules, which seriously affects the stable supply of US chip products.”

“The Chinese auto industry’s confidence in sourcing U.S. chip products has been shaken, and U.S. auto chip products are no longer reliable and safe,” the association said.

With Agence France-Presse and Reuters