The Pentagon is investigating how sensitive technology in the F-35 fighter jet was diverted to Hong Kong and is currently unaccounted for, raising concerns that it could have made its way into the possession of the Chinese military.

The shipment of parts was intended to go from Australia to the United States and included one of the jet’s canopies, which covers the cockpit and contains stealth technology, according to Politico. Instead, the parts for the Lockheed Martin-manufactured plane ended up in Hong Kong, and it’s unclear why or where those parts are now.