Recent footage and photos have surfaced showing China testing advanced uncrewed air vehicles (UAVs) that can fly at high speeds and extreme altitudes. The tests include launches from a drone and even a high-altitude balloon. These vehicles appear to be linked to the MD-22 project—a hypersonic aircraft that first made headlines two years ago.

What’s in the Footage?

The newly emerged video gives us a closer look at three versions of these mysterious air vehicles, marked MD-19, MD-21, an...