China exerts new restrictions on exports of minerals critical to US weapons making

China slapped new export controls on a batch of minerals such as antimony – vital for the U.S. defense industry as a flame-retardant component used in machine bearings – in a move that could send prices in the defense sector soaring.

The little-known metal antimony is used in ammunition, infrared missiles, nuclear weapons and night vision goggles, as well as batteries and photovoltaic equipment. China produced nearly half of the world’s antimony last year.

The limits, which kicked in on Sunday, apply to six antimony-related products, including antimony ore, antimony metals and antimony oxide.

The U.S. consumed some 22,000 tons of antimony last year. China accounted for 63% of U.S. imports of antimony metal and oxide last year, according to the U.S. Geological Survey (USGS). The next largest supplier, Belgium, offered some 8%.

The material is being restricted "in order to safeguard national security and interests, and fulfill international obligations such as non-proliferation," the Chinese Ministry of Commerce said in a statement.

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The U.S. and other nations have been scrambling to scale back their reliance on China for key materials for the defense and energy sectors. Yet still, China is the leading import source for 25 essential minerals, including tungsten, germanium, magnesium, barite, antimony, most rare earths, indium, graphite, gallium, and arsenic.

It’s just the latest in a set of curbs on exports introduced over the past year.

In December, China banned the export of technology to make rare earth magnets, which followed another ban on exporting technology to extract and separate critical materials.

Last year, it slapped export controls on gallium, germanium