The US Pentagon has stopped accepting new F-35 jets after it discovered a magnet used in the stealthy fighter’s engine was made with unauthorised material from China. The aircraft’s maker, Lockheed Martin, found a part used in the jet’s engine was made in China, as the Defence Department and company confirmed on Wednesday (local time). The Defence Contract Management Agency notified the F-35 Joint Program Office on August 19 that an alloy used in magnets in the F-35’s turbo machine pumps was produced in China, office spokesperson Russell Goemaere said in a statement to The Hill. The programme office “temporarily paused the acceptance of new F-35 aircraft to ensure the F-35 program’s compliance” with defence regulations “pertaining to specialty metals,” Goemaere said. Though Lockheed makes the aircraft, Honeywell produces the turbo machine. According to a Lockheed statement, Honeywell was notified in late August by one of their third-tier suppliers for the turbo machine that they were using an alloy sourced from China that was then magnetised in the United States.