This isn’t some super secret spy mission on the part of the Chinese. They know damn well they couldn’t fly something like this through our airspace undetected. They want us to see it. This is literally a “trial balloon” so they could assess our reaction to this situation. At this point, the Chinese must be very pleased.
I have seen speculation by someone in the aviation field that the Chinese almost had to have received prior permission for this flight from the USG.