At least three transport planes from China reportedly flew to Iran in the three days after Israel began attacking Iran’s nuclear program and military command structure, their cargoes and missions unknown.

The UK Telegraph reported on Tuesday that all three of the cargo planes “flew westward along northern China, crossing into Kazakhstan, then south into Uzbekistan and Turkmenistan,” and then dropped off radar screens as they approached Iran.

All three of the planes apparently filed false flight plans that showed their destination as Luxembourg, but none of them flew anywhere near Europe. Later flights from the same region did head toward Luxembourg, which is the home base of the company that operates the aircraft, Cargolux.

Cargolux, which is partially owned by a Chinese company, on Tuesday denied its planes entered Iranian airspace. The company blamed “faulty public tracking data” for creating the appearance of the planes surreptitiously flying into Iranian airspace.

All three of the planes were Boeing 747 cargo planes, which the Telegraph noted are “commonly used for transporting military equipment and weapons, and hired to fly government contract orders.”

Analysts doubted the three planes would be carrying anything quite so provocative as Chinese military equipment for Iran, although China has long supplied Iran with ballistic missile components. China has also attempted to disguise controversial shipments of military hardware to Iran and Libya as innocuous consumer goods, only to have the deception discovered by customs officials.