A Congressional inquiry is underway after sensitive F-35 components reportedly bound from Australia to the U.S. were unexpectedly diverted to Hong Kong, raising concerns that China could gain access to classified military technology. The Pentagon’s F-35 Joint Program Office confirmed a shipment problem involving unserviceable F-35 components and said it is working with U.S. authorities and industry partners to recover the parts and investigate what happened.

The reported shipment included an F-35 cockpit canopy, which contains a transparent radar-absorbing coating important to the aircraft’s stealth capabilities, Military.com reports. Lawmakers worry the technology could be examined or reverse-engineered if the components remain in Chinese-controlled territory.

The incident also highlights vulnerabilities in the F-35’s complex international supply chain, which involves multiple countries, contractors, and commercial shipping providers. A 2023 Government Accountability Office report found that more than 1 million F-35 spare parts had gone missing over a five-year period, underscoring longstanding challenges in tracking the program’s vast inventory.