China’s exports of rare earths fell in September compared with the previous month, as stricter government controls on the strategic materials disrupted global supply chains and heightened trade tensions with Washington.

According to customs data released on Saturday, shipments of rare earth materials — used in electric vehicles, weaponry, and high-tech manufacturing — totaled 6,538 tons, down from 7,338 tons in August.

The decline contrasts with steady increases in previous months that pushed exports in August to their highest level since at least 2012.

Earlier this month, Beijing unveiled sweeping new restrictions on rare earth elements, expanding export controls to include overseas products containing even trace amounts of materials originating from China.