A day after Israel attacked Iran on Friday, a cargo plane took off from China. The next day, a second plane departed from a coastal city. Then on Monday, yet another departed, this time from Shanghai – three flights in three days.

Data showed that on each flight, the plane flew westward along northern China, crossing into Kazakhstan, then south into Uzbekistan and Turkmenistan – and then falling off the radar as it neared Iran.

To add to the mystery, flight plans indicated a final destination of Luxembourg, but the aircraft appeared to have never flown near European skies.

Aviation experts have noted that the type of plane used, Boeing 747 freighters, are commonly used for transporting military equipment and weapons, and hired to fly government contract orders.