On August 19, the Defense Contract Management Agency (DCMA) had issued a notification announcing the discovery of a Chinese alloy magnet within the aircraft's turbomachinery pump. The Defense Federal Acquisition Regulations Supplement (DFARS) strictly prohibits the U.S. Department of Defense (DoD) from purchasing materials or components from China, North Korea, Iran or Russia. In fact, after confirmation, the DoD recently decided not to accept any more F-35s from the factory. For now, only three aircraft seem to be affected and are stationed at Lockheed Martin facilities. On the other hand, the F-35s currently in service are not banned from flight because according to Russell Goemaere, one of the F-35 program's spokesmen, the magnet in question "does not transmit information or adversely affect the integrity of the aircraft and there is no performance, quality, safety or security risk associated with this issue."

Few information is available yet, but it appears that a Lockheed Martin Tier 3 subcontractor may have received Chinese-origin cobalt and samarium to create the magnet via a Tier 5 subcontractor. A solution corresponding to the American rules would have already been found and implemented. As a reminder, the construction of an F-35 requires the assembly of 300,000 parts supplied by 1,700 companies at different levels. The DoD has not yet given a date for the end of deliveries. An investigation has been opened to understand how this could have happened, despite previous investigations into deliveries for this aircraft. Reuters reports, however, that magnets used on the F-35 are also composed of Chinese-origin alloy, but that it had previously received an official waiver.