China will ban exports to the US of items related to gallium, germanium, antimony and superhard materials that have potential military applications, its commerce ministry said on Tuesday, a day after Washington’s latest crackdown on China’s chip sector.

Beijing’s directive on so-called dual-use items, which cites safeguarding national security and interests and takes immediate effect, also requires stricter review of end-usage for graphite items shipped to the United States.

“In principle, the export of gallium, germanium, antimony, and superhard materials to the United States shall not be permitted,” the ministry said.

The curbs strengthen enforcement of existing limits on exports of the critical minerals that Beijing began rolling out last year but apply only to the US in the latest escalation of trade tensions between the world’s two largest economies ahead of President-elect Donald Trump taking office.

However, there have been no Chinese shipments of wrought and unwrought germanium or gallium to the US this year through October, even though it was the fourth and fifth-largest market for the minerals, respectively, a year earlier, Chinese customs data show.

Gallium and germanium are used in semiconductors, while germanium is also used in infrared technology, fibre optic cables and solar cells.

Similarly, China’s overall October shipments of antimony products plunged by 97% from September after Beijing’s move to limit its exports took effect. China accounted last year for 48% of globally mined antimony, which is used in ammunition, infrared missiles, nuclear weapons and night vision goggles, as well as in batteries and photovoltaic equipment.

China’s announcement comes after the United States launched its third crackdown in three years on China’s semiconductor industry on Monday, curbing exports to 140 companies, including chip equipment maker Naura Technology Group.