China has imposed severe restrictions on the export of key minerals needed by Western defense companies, forcing them to look for alternative sources outside the country, industry representatives say, The Wall Street Journal reports.

The reduction in deliveries of rare earth metals and magnets is causing delays in the production of weapons and equipment, from ammunition to drones and fighter jets. One American drone manufacturer was forced to delay orders for several weeks while it searched for alternatives to Chinese components.

Traders said prices for some essential materials have risen five or more times above pre-war levels because of Beijing’s restrictions. More than 80,000 parts used in US weapons contain minerals subject to Chinese export controls, and nearly all supply chains rely on Chinese suppliers, posing serious risks to US defense.

In addition, Chinese authorities are requiring Western companies to provide detailed information about the intended use of the minerals they purchase so they can prevent them from being used in the military sector.