Now that we’ve caught on that China has been sending spy balloons over U.S. territory along the outer edge of the atmosphere, we’re shooting down everything that’s flying at roughly the same altitude and looks even vaguely like it might be another Chinese spy balloon—four such things, as of this writing, in a little more than a week. Many mysteries remain (not least the nature and source of the last three of those four shot-down objects), but a few things seem clear or at least, very likely. Advertisement First, the Chinese have probably been doing this for quite a while....