The U.S. Pentagon has stopped accepting new F-35 jets after it discovered a magnet used in the stealthy fighter's engine was made with unauthorized material from China, a U.S. official said on Wednesday.

An investigation that gathered steam in mid-August found that an alloy in the engine's lubricant pump did not comply with U.S. procurement laws that bar unauthorized Chinese content, said Pentagon spokesperson Russell Goemaere.

Goemaere confirmed the magnet does not transmit information or harm aircraft and that there are no risks involved.

The temporary pause on accepting the stealth fighters was put in place by the F-35 Joint Procurement Office, according to the Flight Global website. The office oversees acquisitions for the Army, Air Force, Navy and Marine Corps.

Lockheed Martin, which manufactures the jets, said "the issue is related to a magnet on the F-35 Turbomachine manufactured by Honeywell that includes cobalt and samarium alloy."

While Lockheed Martin is the main contractor for the F-35, the turbomachine is manufactured by Honeywell.

The magnet that includes the China-sourced metal is produced and supplied by an unidentified subcontractor. The magnet is used in a lubrication pump that is part of the turbomachine.

There are nearly 1,400 companies based in 45 states and Puerto Rico that supply parts for the F-35, according to Lockheed Martin's website.

Honeywell said in an April 2021 statement that it supplies 100 parts for each F-35 built, including avionics, inertial navigation systems, engine fuel controls, cockpit and avionics cooling, wheels and brakes and a thermal management system.

The company told Flight Global that it has stopped working with the supplier who sourced metals from China and expects to begin deliveries from another U.S. firm beginning in October.

There are other Chinese-origin magnets on the jet which have received waivers from past Pentagon officials.